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<!DOCTYPE html>
<html lang="en"><head>
<link rel="icon" href="/logo.svg">
<title>VanJS - Learning by Example</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
@font-face {
font-family: 'Poppins';
font-style: normal;
font-weight: 400;
src: url(https://fonts.gstatic.com/s/poppins/v20/pxiEyp8kv8JHgFVrJJfedw.ttf) format('truetype');
}
</style>
<link rel="stylesheet" href="/code/w3-v1.css">
<link rel="stylesheet" href="/code/prism-v1.css">
<link rel="stylesheet" href="/vanjs.css">
</head>
<body class="line-numbers" data-prismjs-copy="📋">
<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-Q0NB75RY7E"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'G-Q0NB75RY7E');
</script>
<script type="text/javascript" src="/code/prism-v1.js" defer></script><script type="text/javascript" src="/code/van-1.5.2.nomodule.min.js" defer></script><script type="text/javascript" src="/code/diff.min.js" defer></script><script type="text/javascript" src="https://www.gstatic.com/charts/loader.js" defer></script><script type="text/javascript" src="/code/van-x-0.6.1.nomodule.min.js" defer></script><script type="text/javascript" src="demo.js" defer></script>
<!-- Sidebar/menu -->
<nav class="w3-sidebar w3-red w3-collapse w3-top w3-large w3-padding" style="z-index:3;width:280px;font-weight:bold;" id="mySidebar"><br>
<a href="javascript:void(0)" onclick="w3_close()" class="w3-button w3-hide-large w3-display-topleft" style="width:100%;font-size:22px">Close Menu</a>
<div class="w3-container">
<h1 class="w3-padding-16 w3-xxxlarge">
<img src="/logo.svg" alt="VanJS" width="192px" height="192px">
</h1>
</div>
<div id="nav" class="w3-bar-block"><a href="/" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">Home</a><a href="/start" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">Getting Started</a><a href="/tutorial" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">Tutorial</a><a href="/demo" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white current">VanJS by Example</a><a href="/convert" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">HTML/MD to VanJS</a><a href="/vanui" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">VanUI</a><a href="/minivan" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">Mini-Van</a><a href="/ssr" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">SSR & Hydration</a><a href="/x" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">X</a><a href="/advanced" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">Advanced Topics</a><a href="/media" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">Media Coverage</a><a href="/about" onclick="w3_close()" class="w3-bar-item w3-button w3-hover-white">About</a></div>
</nav>
<!-- Top menu on small screens -->
<header class="w3-container w3-top w3-hide-large w3-red w3-xlarge w3-padding">
<a href="javascript:void(0)" class="w3-button w3-red w3-margin-right" onclick="w3_open()">☰</a>
<span id="title-bar">VanJS by Example</span>
</header>
<!-- Overlay effect when opening sidebar on small screens -->
<div class="w3-overlay w3-hide-large" onclick="w3_close()" style="cursor:pointer" title="close side menu" id="myOverlay"></div>
<!-- !PAGE CONTENT! -->
<div class="w3-main" style="margin-left:300px;">
<div id="page">
<div id="content"><h1 class="w3-xxlarge"><b>VanJS</b>: Learning by Example</h1><blockquote><i>Simplicity is the ultimate sophistication.<br><br>-- Apple Inc.</i></blockquote><p>Despite being an <b>ultra-lightweight</b> UI framework, <b>VanJS</b> allows you to write incredibly elegant and expressive code for comprehensive application logic. This page is a curated list of cool things you can do with just a few lines of JavaScript code, including several handy utilities built with <b>VanJS</b>.</p><p>See also <a href="#community-examples" class="w3-hover-opacity">Community Examples</a>.</p><p><button id="random-demo"><span id="dice">🎲 </span>Show Me a Random Demo</button></p><h2 class="w3-xxlarge w3-text-red" id="hello-world"><a class="self-link" href="#hello-world">Hello World!</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>This is the <code class="symbol">Hello World</code> program shown in the <a href="/" class="w3-hover-opacity">Home</a> page:</p><pre><code class="language-js">const Hello = () => div(
p("👋Hello"),
ul(
li("🗺️World"),
li(a({href: "https://vanjs.org/"}, "🍦VanJS")),
),
)
</code></pre><p><b>Demo:</b></p><p id="demo-hello"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/hello">Try on jsfiddle</a></p><p>This is the funnier <code class="symbol">Hello</code> program shown in <a href="/start" class="w3-hover-opacity">Getting Started</a> page:</p><pre><code class="language-js">const sleep = ms => new Promise(resolve => setTimeout(resolve, ms))
const Run = ({sleepMs}) => {
const steps = van.state(0)
;(async () => { for (; steps.val < 40; ++steps.val) await sleep(sleepMs) })()
return pre(() => `${" ".repeat(40 - steps.val)}🚐💨Hello VanJS!${"_".repeat(steps.val)}`)
}
const Hello = () => {
const dom = div()
return div(
dom,
button({onclick: () => van.add(dom, Run({sleepMs: 2000}))}, "Hello 🐌"),
button({onclick: () => van.add(dom, Run({sleepMs: 500}))}, "Hello 🐢"),
button({onclick: () => van.add(dom, Run({sleepMs: 100}))}, "Hello 🚶♂️"),
button({onclick: () => van.add(dom, Run({sleepMs: 10}))}, "Hello 🏎️"),
button({onclick: () => van.add(dom, Run({sleepMs: 2}))}, "Hello 🚀"),
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-hello-fun"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/hello-fun">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="dom-composition-and-manipulation"><a class="self-link" href="#dom-composition-and-manipulation">DOM Composition and Manipulation</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Even without state and state binding, you can build interactive web pages thanks to <b>VanJS</b>'s flexible API for DOM composition and manipulation: <code class="symbol"><a href="/tutorial#api-tags" class="w3-hover-opacity">tag functions</a></code> and <code class="symbol"><a href="/tutorial#api-add" class="w3-hover-opacity">van.add</a></code>. Check out the example below:</p><pre><code class="language-js">const StaticDom = () => {
const dom = div(
div(
button("Dummy Button"),
button(
{onclick: () =>
van.add(dom,
div(button("New Button")),
div(a({href: "https://www.example.com/"}, "This is a link")),
)
},
"Button to Add More Elements"),
button({onclick: () => alert("Hello from 🍦VanJS")}, "Hello"),
),
)
return dom
}
</code></pre><p><b>Demo:</b></p><p id="demo-static"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/static">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="counter"><a class="self-link" href="#counter">Counter</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>The <code class="symbol">Counter App</code> is a good illustration on how to leverage <a href="/tutorial#states" class="w3-hover-opacity">States</a> to make your application reactive. This is the program shown in the <a href="/" class="w3-hover-opacity">Home</a> page:</p><pre><code class="language-js">const Counter = () => {
const counter = van.state(0)
return span(
"❤️ ", counter, " ",
button({onclick: () => ++counter.val}, "👍"),
button({onclick: () => --counter.val}, "👎"),
)
}
</code></pre><p><b>Demo:</b> <span id="demo-counter-simple"></span></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/counter-simple">Try on jsfiddle</a></p><p>This is a slightly advanced version of <code class="symbol">Counter App</code>:</p><pre><code class="language-js">const buttonStyleList = [
["👆", "👇"],
["👍", "👎"],
["🔼", "🔽"],
["⬆️", "⬇️"],
["⏫", "⏬"],
["📈", "📉"],
]
const Counter = ({buttons}) => {
const counter = van.state(0)
const dom = div(
"❤️ ", counter, " ",
button({onclick: () => ++counter.val}, buttons[0]),
button({onclick: () => --counter.val}, buttons[1]),
button({onclick: () => dom.remove()}, "❌"),
)
return dom
}
const CounterSet = () => {
const containerDom = div()
return div(
containerDom,
button({onclick: () => van.add(containerDom,
Counter({buttons: buttonStyleList[Math.floor(Math.random() * buttonStyleList.length)]}))},
"➕",
),
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-counter-advanced"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/counter-advanced">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="stopwatch"><a class="self-link" href="#stopwatch">Stopwatch</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>This is a <code class="symbol">Stopwatch App</code>, similar to the <code class="symbol"><a href="/tutorial#state-typed-child" class="w3-hover-opacity">Timer App</a></code> shown in the tutorial:</p><pre><code class="language-js">const Stopwatch = () => {
const elapsed = van.state(0)
let id
const start = () => id = id || setInterval(() => elapsed.val += .01, 10)
return span(
pre({style: "display: inline;"}, () => elapsed.val.toFixed(2), "s "),
button({onclick: start}, "Start"),
button({onclick: () => (clearInterval(id), id = 0)}, "Stop"),
button({onclick: () => (clearInterval(id), id = 0, elapsed.val = 0)}, "Reset"),
)
}
</code></pre><p><b>Demo:</b> <span id="demo-stopwatch"></span></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/stopwatch">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="blog"><a class="self-link" href="#blog">Blog</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p><b>VanJS</b> doesn't have an equivalent to React's <code class="symbol"><a href="https://react.dev/reference/react/Fragment" class="w3-hover-opacity"><Fragment></a></code>. For most of the cases, returning an array of HTML elements from your custom component would serve the similar purpose. Here is the sample code equivalent to the <code class="symbol">Blog</code> example in React's official website:</p><pre><code class="language-js">const Blog = () => [
Post({title: "An update", body: "It's been a while since I posted..."}),
Post({title: "My new blog", body: "I am starting a new blog!"}),
]
const Post = ({title, body}) => [
PostTitle({title}),
PostBody({body}),
]
const PostTitle = ({title}) => h1(title)
const PostBody = ({body}) => article(p(body))
</code></pre><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/blog">Try on jsfiddle</a></p><p>The sample code in React is 29 lines. Thus <b>VanJS</b>'s equivalent code is ~3 times shorter by eliminating unnecessary boilerplate.</p><p>Note that: The result of the binding function of a <a href="/tutorial#state-derived-child" class="w3-hover-opacity">state-derived child node</a> can't be an array of elements. You can wrap the result into a pass-through container (<code class="language-html"><span></code> for inline elements and <code class="language-html"><div></code> for block elements) if multiple elements need to be returned.</p><h2 class="w3-xxlarge w3-text-red" id="list"><a class="self-link" href="#list">List</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>As an <b>unopinionated</b> framework, <b>VanJS</b> supports multiple programming paradigms. You can construct the DOM tree in an imperative way (modifying the DOM tree via <code class="symbol"><a href="/tutorial#api-add" class="w3-hover-opacity">van.add</a></code>), or in a functional/declarative way.</p><p>Below is an example of building a list even numbers in <code class="symbol">1..N</code>, using an imperative way:</p><pre><code class="language-js">const EvenNumbers = ({N}) => {
const listDom = ul()
for (let i = 1; i <= N; ++i)
if (i % 2 === 0)
van.add(listDom, li(i))
return div(
p("List of even numbers in 1.." + N + ":"),
listDom,
)
}</code></pre><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/list-imperative">Try on jsfiddle</a></p><p>Alternatively, you can build a list of even numbers in <code class="symbol">1..N</code>, using a functional/declarative way:</p><pre><code class="language-js">const EvenNumbers = ({N}) => div(
p("List of even numbers in 1.." + N + ":"),
ul(
Array.from({length: N}, (_, i) => i + 1)
.filter(i => i % 2 === 0)
.map(i => li(i)),
),
)
</code></pre><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/list-declarative">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="todo-list"><a class="self-link" href="#todo-list">TODO List</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Similarly, to build reactive applications, you can build in a procedural way, which updates UI via the integration with native DOM API (it's easy to do with <b>VanJS</b> as it doesn't introduce an ad-hoc virtual-DOM layer), or in a functional/reactive way, which delegates UI changes to <a href="/tutorial#state-binding" class="w3-hover-opacity">State Binding</a>. You can also choose a hybrid approach between the 2 paradigms, depending on which approach fits well for a specific problem.</p><blockquote><i>道可道，非常道<br>(A rule that can be told by words, is not the rule that should universally apply)<br><br>-- 老子，道德经</i></blockquote><p>Below is an example of building a <code class="symbol">TODO List</code> in a completely procedural way:</p><pre><code class="language-js">const TodoItem = ({text}) => div(
input({type: "checkbox", onchange: e =>
e.target.closest("div").querySelector("span").style["text-decoration"] =
e.target.checked ? "line-through" : ""
}),
span(text),
a({onclick: e => e.target.closest("div").remove()}, "❌"),
)
const TodoList = () => {
const inputDom = input({type: "text"})
const dom = div(
inputDom,
button({onclick: () => van.add(dom, TodoItem({text: inputDom.value}))}, "Add"),
)
return dom
}
</code></pre><p><b>Demo:</b></p><p id="demo-todo-procedural"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/todo-procedural">Try on jsfiddle</a></p><p>Alternatively, you can use a functional/reactive way to build <code class="symbol">TODO Items</code>:</p><pre><code class="language-js">const TodoItem = ({text}) => {
const done = van.state(false), deleted = van.state(false)
return () => deleted.val ? null : div(
input({type: "checkbox", checked: done, onclick: e => done.val = e.target.checked}),
() => (done.val ? del : span)(text),
a({onclick: () => deleted.val = true}, "❌"),
)
}
const TodoList = () => {
const inputDom = input({type: "text"})
const dom = div(
inputDom,
button({onclick: () => van.add(dom, TodoItem({text: inputDom.value}))}, "Add"),
)
return dom
}
</code></pre><p><b>Demo:</b></p><p id="demo-todo-functional"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/todo-functional">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="todo-app"><a class="self-link" href="#todo-app">A Fully Reactive TODO App</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>You can also go fully reactive for the <code class="symbol">TODO App</code>. That is, the entire state of the app is captured by a global <code class="symbol">appState</code>. With the full reactivity it's easier to persist the <code class="symbol">appState</code> into <code class="symbol"><a href="https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage" class="w3-hover-opacity">localStorage</a></code> so that the state is kept across page reloads.</p><p>Note that even if the app is fully reactive, we don't need to re-render the whole DOM tree for state updates, thanks to the optimization with <a href="/tutorial#stateful-binding" class="w3-hover-opacity">stateful binding</a>.</p><p><i>The code was implemented in TypeScript.</i></p><pre><code class="language-ts">class TodoItemState {
constructor(public text: string, public done: State<boolean>, public deleted: State<boolean>) {}
serialize() { return {text: this.text, done: this.done.val} }
}
const TodoItem = ({text, done, deleted}: TodoItemState) => () => deleted.val ? null : div(
input({type: "checkbox", checked: done, onclick: e => done.val = e.target.checked}),
() => (done.val ? del : span)(text),
a({onclick: () => deleted.val = true}, "❌"),
)
class TodoListState {
private constructor(public todos: TodoItemState[]) {}
save() {
localStorage.setItem("appState", JSON.stringify(
(this.todos = this.todos.filter(t => !t.deleted.val)).map(t => t.serialize())))
}
static readonly load = () => new TodoListState(
JSON.parse(localStorage.getItem("appState") ?? "[]")
.map((t: any) => new TodoItemState(t.text, van.state(t.done), van.state(false)))
)
add(text: string) {
this.todos.push(new TodoItemState(text, van.state(false), van.state(false)))
return new TodoListState(this.todos)
}
}
const TodoList = () => {
const appState = van.state(TodoListState.load())
van.derive(() => appState.val.save())
const inputDom = input({type: "text"})
return div(
inputDom, button({onclick: () => appState.val = appState.val.add(inputDom.value)}, "Add"),
(dom?: Element) => dom ?
van.add(dom, TodoItem(appState.val.todos.at(-1)!)) :
div(appState.val.todos.map(TodoItem)),
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-todo-fully-reactive"></p><p><a href="https://codesandbox.io/p/sandbox/github/vanjs-org/vanjs-org.github.io/tree/master/code/todo-app?file=/src/main.ts:1,1" class="w3-hover-opacity">Try on CodeSandbox</a></p><p>With the help of <a href="/x" class="w3-hover-opacity"><b>VanX</b></a>, the code above can be simplified to just 10+ lines:</p><pre><code class="language-js">const TodoList = () => {
const items = vanX.reactive(JSON.parse(localStorage.getItem("appState") ?? "[]"))
van.derive(() => localStorage.setItem("appState", JSON.stringify(vanX.compact(items))))
const inputDom = input({type: "text"})
return div(
inputDom, button({onclick: () => items.push({text: inputDom.value, done: false})}, "Add"),
vanX.list(div, items, ({val: v}, deleter) => div(
input({type: "checkbox", checked: () => v.done, onclick: e => v.done = e.target.checked}),
() => (v.done ? del : span)(v.text),
a({onclick: deleter}, "❌"),
)),
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-todo-fully-reactive-vanx"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/todo-fully-reactive-vanx">Try on jsfiddle</a></p><p>You can refer to <code class="symbol"><a href="/x#reactive-list" class="w3-hover-opacity">vanX.list</a></code> for more details.</p><p><i>You can also check <a href="https://github.com/vanjs-org/van/discussions/316" class="w3-hover-opacity">the example</a> by <a href="https://github.com/ArcaneEngineer" class="w3-hover-opacity">@ArcaneEngineer</a>, which is a slight variation of this <code class="symbol">TODO App</code> to allow TODO items to be editable.</i></p><h2 class="w3-xxlarge w3-text-red" id="game"><a class="self-link" href="#game">Fun Game: Emojis Pops</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>We're able to implement a mini game engine with <b>VanJS</b> in just a few lines. Here is a fun game implemented under 60 lines with the help of <b>VanJS</b> and <a href="x" class="w3-hover-opacity"><b>VanX</b></a>:</p><pre><code class="language-js">const Game = () => {
const time = van.state(60), score = van.state(0), inGame = van.state(false), items = vanX.reactive([])
const fps = 60, height = 400, frameFns = Array(fps * time.val).fill().map(() => [])
let curFrame = 0
const Item = ({val: v}, deleter) => {
const x = Math.floor(Math.random() * (document.body.clientWidth - 42)), y = van.state(0)
let deleted = false
v.removing = false
van.derive(() => v.removing &&
nextFrames(Math.floor(0.3 * fps)).then(() => (deleted = true, deleter())))
;(async () => {
do { await nextFrames(1) } while (!deleted && (y.val += v.speed) <= height)
v.removing || deleter()
})()
return span({
class: "item",
style: () => `left: ${x}px; bottom: ${y.val}px; opacity: ${v.removing ? 0 : 1};`,
onclick: () => inGame.val && !v.removing &&
frameFns[curFrame].push(() => (v.removing = v.msg, v.action())),
}, v.icon, () => v.removing ? span({class: "msg " + (v.bad ? "bad": "good")}, v.removing) : "")
}
const itemTypes = [
{icon: "👍", speed: 5, n: 60, msg: "+1", action: () => ++score.val},
{icon: "🚀", speed: 10, n: 12, msg: "+10", action: () => score.val += 10},
{icon: "👎", speed: 3, n: 60, msg: "-5", bad: true, action: () => score.val -= 5},
{icon: "🐌", speed: 5, n: 6, msg: "Slowed", action: () => items.forEach(it => it.speed /= 2)},
{icon: "💣", speed: 3, n: 60, msg: "BOOM!", bad: true, action: () =>
items.forEach(it => it.removing = "BOOM!")},
]
const begin = () => {
setInterval(() => {
if (!inGame.val) return
for (const fn of frameFns[curFrame]) fn()
++curFrame % 60 === 0 && --time.val
curFrame === frameFns.length && end()
}, 1000 / fps)
inGame.val = true
for (const type of itemTypes)
for (let i = 0; i < type.n; ++i)
frameFns[Math.floor(Math.random() * frameFns.length)].push(() => items.push({...type}))
}
const end = () => (alert("Your score: " + score.val), location.reload())
const nextFrames = n => new Promise(r => frameFns[curFrame + n]?.push(r))
return div({class: "root"},
span({class: "time"}, "Time: ", time), span({class: "score"}, "Score: ", score),
vanX.list(() => div({class: "board"}), items, Item),
div({class: "panel"},
button({onclick: () => curFrame ? inGame.val = !inGame.val : begin()},
() => inGame.val ? "Pause" : "Start",
),
),
)
}
</code></pre><p><a href="/code/game" class="w3-hover-opacity">🎮 Let's play!</a> (you can share your score here: <a href="https://github.com/vanjs-org/van/discussions/174" class="w3-hover-opacity">#174</a>)</p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/game">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="code-browser"><a class="self-link" href="#code-browser">SPA w/ Client-Side Routing: Code Browser</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>With <b>VanJS</b>, you can built a single-page application with client-side routing support, thanks to <b>VanJS</b>'s powerful builtin state management and state derivation:</p><pre><code class="language-ts">const Browser = () => {
const file = van.state(location.hash.slice(1))
window.addEventListener("hashchange", () => file.val = location.hash.slice(1))
const text = van.derive(() => file.val ? (
fetch("https://api.github.com/repos/vanjs-org/van/contents/src/" + file.val)
.then(r => r.json())
.then(json => text.val = {lang: file.val.split(".").at(-1), str: atob(json.content)})
.catch(e => text.val = {str: e.toString()}),
{str: "Loading"}
) : {str: "Select a file to browse"})
const files = van.state([])
fetch("https://api.github.com/repos/vanjs-org/van/contents/src")
.then(r => r.json())
.then(json => files.val = json.map(f => f.name).filter(n => /\.(ts|js)$/.test(n)))
.catch(e => text.val = {str: e.toString()})
const browseFile = e => {
e.preventDefault()
history.pushState({}, "", new URL(e.target.href).hash)
dispatchEvent(new Event("hashchange"))
}
return div({class: "row"},
div({class: "left"}, ul(li({class: "folder"}, "src", () => ul(
files.val.map(f => li({class: "file"},
a({href: "#" + f, class: () => f === file.val ? "selected" : "", onclick: browseFile}, f),
)),
)))),
(dom = div({class: "right"}, pre(code()))) => {
const codeDom = dom.querySelector("code")
codeDom.textContent = text.val.str
codeDom.className = text.val.lang ? "language-" + text.val.lang : ""
if (text.val.lang) setTimeout(() => Prism.highlightAll(), 5)
return dom
},
)
}
</code></pre><p><a href="https://codesandbox.io/p/sandbox/github/vanjs-org/vanjs-org.github.io/tree/master/code/code-browser?file=/src/main.js:1,1" class="w3-hover-opacity">Try on CodeSandbox</a></p><h2 class="w3-xxlarge w3-text-red" id="stargazers"><a class="self-link" href="#stargazers">Stargazers</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>The following code can show the number of stars for a Github repo, and a list of most recent stargazers:</p><pre><code class="language-js">const Stars = async repo => {
const repoJson = await fetch(`https://api.github.com/repos/${repo}`).then(r => r.json())
const pageNum = Math.floor((repoJson.stargazers_count - 1) / 100) + 1
const starsJson = await fetch(
`https://api.github.com/repos/${repo}/stargazers?per_page=100&page=${pageNum}`)
.then(r => r.json())
return div(
p(repoJson.stargazers_count, " ⭐️:"),
ul(
starsJson.reverse().map(u => li(a({href: u.html_url}, u.login))),
),
)
}
</code></pre><p><a href="code/stars" class="w3-hover-opacity">Try it out here</a></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/starts">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="epoch-timestamp-converter"><a class="self-link" href="#epoch-timestamp-converter">Epoch Timestamp Converter</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Below is an application which converts a Unix epoch timestamp into a human-readable datetime string:</p><pre><code class="language-js">const tsToDate = ts =>
ts < 1e10 ? new Date(ts * 1e3) :
ts < 1e13 ? new Date(ts) :
ts < 1e16 ? new Date(ts / 1e3) :
new Date(ts / 1e6)
const Converter = () => {
const nowTs = van.state(Math.floor(new Date().getTime() / 1e3)), date = van.state(null)
setInterval(() => ++nowTs.val, 1000)
const inputDom = input({type: "text", size: 25, value: nowTs.val})
return div(
div(b("Now: "), nowTs),
inputDom, " ",
button({onclick: () => date.val = tsToDate(Number(inputDom.value))}, "Convert"),
p(i("Supports Unix timestamps in seconds, milliseconds, microseconds and nanoseconds.")),
() => date.val ? p(
div(date.val.toString()),
div(b("GMT: "), date.val.toGMTString()),
) : p(),
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-epoch-converter"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/epoch-converter">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="keyboard-event-inspector"><a class="self-link" href="#keyboard-event-inspector">Keyboard Event Inspector</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Below is an application to inspect all relevant key codes in keyboard <code class="symbol"><a href="https://developer.mozilla.org/en-US/docs/Web/API/Element/keydown_event" class="w3-hover-opacity">keydown</a></code> events:</p><pre><code class="language-js">const Label = text => span({class: "label"}, text)
const Value = text => span({class: "value"}, text)
const Inspector = () => {
const keyEvent = van.state(new KeyboardEvent("keydown"))
const Result = prop => span(Label(prop + ": "), Value(() => keyEvent.val[prop]))
return div(
div(input({placeholder: "Focus here and press keys…", style: "width: 260px",
onkeydown: e => (e.preventDefault(), keyEvent.val = e)})),
div(Result("key"), Result("code"), Result("which"), Result("keyCode")),
div(Result("ctrlKey"), Result("metaKey"), Result("altKey"), Result("shiftKey")),
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-key-inspector"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/key-inspector">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="diff"><a class="self-link" href="#diff">Diff</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Here is a <code class="symbol">Diff App</code> with the integration of <code class="symbol"><a href="https://github.com/kpdecker/jsdiff" class="w3-hover-opacity">jsdiff</a></code>. The app can compare 2 pieces of text (very handy tool to check how your text is revised by <code class="symbol">ChatGPT</code> 🙂):</p><pre><code class="language-js">const autoGrow = e => {
e.target.style.height = "5px"
e.target.style.height = (e.target.scrollHeight + 5) + "px"
}
const DiffApp = () => {
const oldTextDom = textarea({oninput: autoGrow, rows: 1})
const newTextDom = textarea({oninput: autoGrow, rows: 1})
const diff = van.state([])
return div(
div({class: "row"},
div({class: "column"}, oldTextDom), div({class: "column"}, newTextDom),
),
div({class: "row"},
button({onclick: () => diff.val = Diff.diffWords(oldTextDom.value, newTextDom.value)},
"Diff",
),
),
div({class: "row"}, () => div({class: "column", style: "white-space: pre-wrap;"},
diff.val.map(d => span({class: d.added ? "add" : (d.removed ? "remove" : "")}, d.value)),
)),
)
}</code></pre><p><b>Demo:</b></p><p id="demo-diff-simple"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/diff-simple">Try on jsfiddle</a></p><p>Here is a more advanced <code class="symbol">Diff App</code> that supports side-by-side and line-by-line comparison:</p><pre><code class="language-js">const autoGrow = e => {
e.target.style.height = "5px"
e.target.style.height = (e.target.scrollHeight + 5) + "px"
}
const Line = ({diff, skipAdd, skipRemove}) => div(
{class: "column", style: "white-space: pre-wrap;"},
diff.filter(d => !(skipAdd && d.added || skipRemove && d.removed)).map(d =>
span({class: d.added ? "add" : (d.removed ? "remove" : "")}, d.value)),
)
const DiffLine = (oldLine, newLine, showMerged) => {
const diff = Diff.diffWords(oldLine, newLine)
return div({class: "row" + (showMerged ? " merged" : "")},
showMerged ?
Line({diff}) : [Line({diff, skipAdd: true}), Line({diff, skipRemove: true})],
)
}
const DiffApp = () => {
const oldTextDom = textarea({oninput: autoGrow, rows: 1})
const newTextDom = textarea({oninput: autoGrow, rows: 1})
const diff = van.state([])
const showMerged = van.state(true)
return div(
div({class: "row"},
div({class: "column"}, oldTextDom), div({class: "column"}, newTextDom),
),
div({class: "row"},
button({onclick: () => diff.val = Diff.diffLines(oldTextDom.value, newTextDom.value)},
"Diff",
),
input({type: "checkbox", checked: showMerged,
oninput: e => showMerged.val = e.target.checked}),
"show merged result"
),
() => {
const diffVal = diff.val, showMergedVal = showMerged.val, resultDom = div()
for (let i = 0; i < diffVal.length; ) {
let line
if (diffVal[i].added && diffVal[i + 1]?.removed) {
line = DiffLine(diffVal[i + 1].value, diffVal[i].value, showMergedVal)
i += 2
} else if (diffVal[i].removed && diffVal[i + 1]?.added) {
line = DiffLine(diffVal[i].value, diffVal[i + 1].value, showMergedVal)
i += 2
} else if (diffVal[i].added) {
line = showMergedVal ? div({class: "merged add row"},
div({class: "column", style: "white-space: pre-wrap;"}, diffVal[i].value),
) : div({class: "row"},
div({class: "column"}),
div({class: "add column", style: "white-space: pre-wrap;"}, diffVal[i].value),
)
++i
} else if (diffVal[i].removed) {
line = showMergedVal ? div({class: "merged remove row"},
div({class: "column", style: "white-space: pre-wrap;"}, diffVal[i].value),
) : div({class: "row"},
div({class: "remove column", style: "white-space: pre-wrap;"}, diffVal[i].value),
)
++i
} else {
line = div({class: "row", style: "white-space: pre-wrap;"},
showMergedVal ? div({class: "merged column"}, diffVal[i].value) :
[
div({class: "column"}, diffVal[i].value),
div({class: "column"}, diffVal[i].value),
],
)
++i
}
van.add(resultDom, line)
}
return resultDom
},
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-diff"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/diff">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="calculator"><a class="self-link" href="#calculator">Calculator</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>The code below implements a <code class="symbol">Calculator App</code> similar to the one that you are using on your smartphones:</p><pre><code class="language-js">const Calculator = () => {
let lhs = van.state(null), op = null, rhs = van.state(0)
const calc = (lhs, op, rhs) =>
!op || lhs === null ? rhs :
op === "+" ? lhs + rhs :
op === "-" ? lhs - rhs :
op === "x" ? lhs * rhs : lhs / rhs
const onclick = e => {
const str = e.target.innerText
if (str >= "0" && str <= "9")
typeof rhs.val === "string" ? rhs.val += str : rhs.val = rhs.val * 10 + Number(str)
else if (str === "AC") lhs.val = op = null, rhs.val = 0
else if (str === "+/-" && rhs.val) rhs.val = -rhs.val
else if (str === "%" && rhs.val) rhs.val *= 0.01
else if (str === "+" || str === "-" || str === "x" || str === "÷") {
if (rhs.val !== null) lhs.val = calc(lhs.val, op, Number(rhs.val)), rhs.val = null
op = str
} else if (str === "=" && op && rhs.val !== null)
lhs.val = calc(lhs.val, op, Number(rhs.val)), op = null, rhs.val = null
else if (str === ".")
rhs.val = rhs.val ? rhs.val + "." : "0."
}
const Button = str => div({class: "button"}, button(str))
return div({id: "root"},
div({id: "display"}, div(() => rhs.val ?? lhs.val)),
div({id: "panel", onclick},
div(Button("AC"), Button("+/-"), Button("%"), Button("÷")),
div(Button("7"), Button("8"), Button("9"), Button("x")),
div(Button("4"), Button("5"), Button("6"), Button("-")),
div(Button("1"), Button("2"), Button("3"), Button("+")),
div(div({class: "button wide"}, button("0")), Button("."), Button("=")),
),
)
}
</code></pre><p><b>Demo:</b></p><iframe id="demo-calculator" src="/code/calculator.html"></iframe><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/calculator">Try on jsfiddle</a></p><p>Notably, this <code class="symbol">Calculator App</code> is equivalent to the React-based implementation here: <a href="https://github.com/ahfarmer/calculator" class="w3-hover-opacity">github.com/ahfarmer/calculator</a>. Here is the size comparison of the total package between the 2 apps:</p><table style="text-align: right;"><thead><tr><th></th><th>VanJS-based App</th><th>React-based App</th></tr></thead><tbody><tr><td><b># of files:</b></td><td>2</td><td>16</td></tr><tr><td><b># of lines:</b></td><td>143</td><td>616</td></tr></tbody></table><p>As you can see, not only <b>VanJS</b> is <b>~50 times</b> smaller than React, apps built with <b>VanJS</b> also tends to be much slimmer.</p><h2 class="w3-xxlarge w3-text-red" id="table-viewer"><a class="self-link" href="#table-viewer">Table-View Example: JSON/CSV Table Viewer</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>The following code implements a <code class="symbol">Table Viewer</code> for JSON/CSV-based data by leveraging <a href="/tutorial#fun-dom" class="w3-hover-opacity">functional-style DOM tree building</a>:</p><pre><code class="language-js">const TableViewer = ({inputText, inputType}) => {
const jsonRadioDom = input({type: "radio", checked: inputType === "json",
name: "inputType", value: "json"})
const csvRadioDom = input({type: "radio", checked: inputType === "csv",
name: "inputType", value: "csv"})
const autoGrow = e => {
e.style.height = "5px"
e.style.height = (e.scrollHeight + 5) + "px"
}
const textareaDom = textarea({oninput: e => autoGrow(e.target)}, inputText)
setTimeout(() => autoGrow(textareaDom), 10)
const text = van.state("")
const tableFromJson = text => {
const json = JSON.parse(text), head = Object.keys(json[0])
return {
head,
data: json.map(row => head.map(h => row[h]))
}
}
const tableFromCsv = text => {
const lines = text.split("\n").filter(l => l.length > 0)
return {
head: lines[0].split(","),
data: lines.slice(1).map(l => l.split(",")),
}
}
return div(
div(jsonRadioDom, label("JSON"), csvRadioDom, label("CSV (Quoting not Supported)")),
div(textareaDom),
div(button({onclick: () => text.val = textareaDom.value}, "Show Table")),
p(() => {
if (!text.val) return div()
try {
const {head, data} = (jsonRadioDom.checked ? tableFromJson : tableFromCsv)(text.val)
return table(
thead(tr(head.map(h => th(h)))),
tbody(data.map(row => tr(row.map(col => td(col))))),
)
} catch (e) {
return pre({class: "err"}, e.toString())
}
}),
)
}
</code></pre><p><b>Demo:</b></p><p id="demo-table-viewer"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/table-viewer">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="package-lock-inspector"><a class="self-link" href="#package-lock-inspector"><code class="symbol">package-lock.json</code> Inspector</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Below is an example which can extract and display all dependency packages and their versions from <code class="symbol">package-lock.json</code> file:</p><pre><code class="language-js">const PackageLockInspector = () => {
const json = van.state("")
return [
div("Paste the content of package-lock.json file here:"),
textarea({rows: 10, cols: 80, oninput: e => json.val = e.target.value}),
() => {
if (!json.val) return div()
try {
const packages = Object.entries(JSON.parse(json.val).packages).filter(([k]) => k)
return div(
h4("All Dependencies (", packages.length, ")"),
table(
thead(tr(th("Package"), th("Version"))),
tbody(packages.map(([k, {version}]) => {
const name = k.slice("node_modules/".length)
return tr(
td(a({href: "https://www.npmjs.com/package/" + name}, name)),
td(a({href: `https://www.npmjs.com/package/${name}/v/${version}`}, version)),
)
})),
),
)
} catch (e) {
return pre({style: "color: red;"}, "Parsing error: ", e.toString())
}
},
]
}
</code></pre><p><a href="code/package-lock-inspector" class="w3-hover-opacity">Try it out here</a></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/package-lock-inspector">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="json-inspector"><a class="self-link" href="#json-inspector">Tree-View Example: JSON Inspector</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>This is another example of leveraging <a href="/tutorial#fun-dom" class="w3-hover-opacity">functional-style DOM tree building</a> - to build a tree view for inspecting JSON data:</p><pre><code class="language-js">const ListItem = ({key, value, indent = 0}) => {
const hide = van.state(key !== "")
const valueDom = typeof value !== "object" ? value : div(
{style: () => hide.val ? "display: none;" : ""},
Object.entries(value).map(([k, v]) =>
ListItem({key: k, value: v, indent: indent + 2 * (key !== "")})),
)
return (key ? div : pre)(
" ".repeat(indent),
key ? (
typeof valueDom !== "object" ? ["🟰 ", b(`${key}: `)] :
a({onclick: () => hide.val = !hide.val, style: "cursor: pointer"},
() => hide.val ? "➕ " : "➖ ", b(`${key}: `), () => hide.val ? "…" : "",
)
) : [],
valueDom,
)
}
const JsonInspector = ({initInput}) => {
const autoGrow = e => {
e.style.height = "5px"
e.style.height = (e.scrollHeight + 5) + "px"
}
const textareaDom = textarea({oninput: e => autoGrow(e.target)}, initInput)
setTimeout(() => autoGrow(textareaDom), 10)
const errmsg = van.state(""), json = van.state(null)
const inspect = () => {
try {
json.val = JSON.parse(textareaDom.value)
errmsg.val = ""
} catch (e) {
errmsg.val = e.message
}
}
return div(
div(textareaDom),
div(button({onclick: inspect}, "Inspect")),
pre({style: "color: red"}, errmsg),
() => json.val ? ListItem({key: "", value: json.val}) : "",
)
}</code></pre><p><b>Demo:</b></p><p id="demo-json-inspector"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/json-inspector">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="auto-complete"><a class="self-link" href="#auto-complete">Textarea with Autocomplete</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>The code below implements a <code class="symbol"><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/textarea" class="w3-hover-opacity">textarea</a></code> with autocomplete support. This implementation leverages <a href="/tutorial#stateful-binding" class="w3-hover-opacity">Stateful DOM binding</a> to optimize the performance of DOM tree rendering:</p><p><i>The code was implemented in TypeScript to validate <b>VanJS</b>'s TypeScript support.</i></p><pre><code class="language-ts">interface SuggestionListProps {
readonly candidates: readonly string[]
readonly selectedIndex: number
}
const SuggestionList = ({candidates, selectedIndex}: SuggestionListProps) =>
div({class: "suggestion"}, candidates.map((s, i) => pre({
"data-index": i,
class: i === selectedIndex ? "text-row selected" : "text-row",
}, s)))
const lastWord = (text: string) => text.match(/\w+$/)?.[0] ?? ""
const AutoComplete = ({words}: {readonly words: readonly string[]}) => {
const getCandidates = (prefix: string) => {
const maxTotal = 10, result: string[] = []
for (let word of words) {
if (word.startsWith(prefix.toLowerCase())) result.push(word)
if (result.length >= maxTotal) break
}
return result
}
const prefix = van.state("")
const candidates = van.derive(() => getCandidates(prefix.val))
// Resetting selectedIndex to 0 whenever candidates change
const selectedIndex = van.derive(() => (candidates.val, 0))
const onkeydown = (e: KeyboardEvent) => {
if (e.key === "ArrowDown") {
selectedIndex.val = selectedIndex.val + 1 < candidates.val.length ? selectedIndex.val + 1 : 0
e.preventDefault()
} else if (e.key === "ArrowUp") {
selectedIndex.val = selectedIndex.val > 0 ? selectedIndex.val - 1 : candidates.val.length - 1
e.preventDefault()
} else if (e.key === "Enter") {
const candidate = candidates.val[selectedIndex.val] ?? prefix.val
const target = <HTMLTextAreaElement>e.target
target.value += candidate.substring(prefix.val.length)
target.setSelectionRange(target.value.length, target.value.length)
prefix.val = lastWord(target.value)
e.preventDefault()
}
}
const oninput = (e: Event) => prefix.val = lastWord((<HTMLTextAreaElement>e.target).value)
return div({class: "root"}, textarea({onkeydown, oninput}), (dom?: Element) => {
if (dom && candidates.val === candidates.oldVal) {
// If the candidate list doesn't change, we don't need to re-render the
// suggestion list. Just need to change the selected candidate.
dom.querySelector(`[data-index="${selectedIndex.oldVal}"]`)
?.classList?.remove("selected")
dom.querySelector(`[data-index="${selectedIndex.val}"]`)
?.classList?.add("selected")
return dom
}
return SuggestionList({candidates: candidates.val, selectedIndex: selectedIndex.val})
})
}
</code></pre><p><b>Demo:</b></p><p id="demo-auto-complete-stateful-binding"></p><p id="jsfiddle-auto-complete-stateful-binding"><a href="https://jsfiddle.net/p5e71ryw/">Try on jsfiddle</a></p><p>Alternatively, we can implement the same app with <a href="/tutorial#state-derived-prop" class="w3-hover-opacity">State-derived properties</a>:</p><p><i>The code was implemented in TypeScript to validate <b>VanJS</b>'s TypeScript support.</i></p><pre><code class="language-ts">const lastWord = (text: string) => text.match(/\w+$/)?.[0] ?? ""
const AutoComplete = ({words}: {readonly words: readonly string[]}) => {
const maxTotalCandidates = 10
const getCandidates = (prefix: string) => {
const result: string[] = []
for (let word of words) {
if (word.startsWith(prefix.toLowerCase())) result.push(word)
if (result.length >= maxTotalCandidates) break
}
return result
}
const prefix = van.state("")
const candidates = van.derive(() => getCandidates(prefix.val))
// Resetting selectedIndex to 0 whenever candidates change
const selectedIndex = van.derive(() => (candidates.val, 0))
const SuggestionListItem = ({index}: {index: number}) => pre(
{class: () => index === selectedIndex.val ? "text-row selected" : "text-row"},
() => candidates.val[index] ?? "",
)
const suggestionList = div({class: "suggestion"},
Array.from({length: 10}).map((_, index) => SuggestionListItem({index})))
const onkeydown = (e: KeyboardEvent) => {
if (e.key === "ArrowDown") {
selectedIndex.val = selectedIndex.val + 1 < candidates.val.length ? selectedIndex.val + 1 : 0
e.preventDefault()
} else if (e.key === "ArrowUp") {
selectedIndex.val = selectedIndex.val > 0 ? selectedIndex.val - 1 : candidates.val.length - 1
e.preventDefault()
} else if (e.key === "Enter") {
const candidate = candidates.val[selectedIndex.val] ?? prefix.val
const target = <HTMLTextAreaElement>e.target
target.value += candidate.substring(prefix.val.length)
target.setSelectionRange(target.value.length, target.value.length)
prefix.val = lastWord(target.value)
e.preventDefault()
}
}
const oninput = (e: Event) => prefix.val = lastWord((<HTMLTextAreaElement>e.target).value)
return div({class: "root"}, textarea({onkeydown, oninput}), suggestionList)
}
</code></pre><p><b>Demo:</b></p><p id="demo-auto-complete-derived-props"></p><p id="jsfiddle-auto-complete-derived-props"><a href="https://jsfiddle.net/7ueod0pL/1/">Try on jsfiddle</a></p><h2 class="w3-xxlarge w3-text-red" id="html-md-to-vanjs-code-converter"><a class="self-link" href="#html-md-to-vanjs-code-converter">HTML/MD to VanJS Code Converter</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>The <a href="/convert" class="w3-hover-opacity">online UI</a> for the HTML/MD snippet to <b>VanJS</b> <a href="https://github.com/vanjs-org/converter" class="w3-hover-opacity">code converter</a>, is also implemented with <b>VanJS</b>.</p><p>Source code: <code class="symbol"><a href="https://github.com/vanjs-org/vanjs-org.github.io/tree/master/converter-ui/convert.ts" class="w3-hover-opacity">convert.ts</a></code></p><h2 class="w3-xxlarge w3-text-red" id="jupyter-like-javascript-console"><a class="self-link" href="#jupyter-like-javascript-console">Jupyter-like JavaScript Console</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Next up, we're going to demonstrate a simplified Jupyter-like JavaScript console implemented in <b>~100 lines</b> of code with <b>VanJS</b>. The JavaScript console supports drawing tables (with the technique similar to <a href="#table-viewer" class="w3-hover-opacity">Table Viewer</a>), inspecting objects in a tree view (with the technique similar to <a href="#json-inspector" class="w3-hover-opacity">Json Inspector</a>) and plotting (with the integration of <a href="https://developers.google.com/chart" class="w3-hover-opacity">Google Charts</a>).</p><p>Here is the implementation:</p><pre><code class="language-js">const toDataArray = data => {
const hasPrimitive = !data.every(r => typeof r === "object")
const keys = [...new Set(
data.flatMap(r => typeof r === "object" ? Object.keys(r) : []))]
return [
(hasPrimitive ? ["Value"] : []).concat(keys),
...data.map(r =>
(typeof r === "object" ? (hasPrimitive ? [""] : []) : [r]).concat(
keys.map(k => r[k] ?? "")
)),
]
}
const table = data => {
const dataArray = toDataArray(data)
return van.tags.table(
thead(tr(th("(index)"), dataArray[0].map(k => th(k)))),
tbody(dataArray.slice(1).map((r, i) => tr(td(i), r.map(c => td(c))))),
)
}
const plot = (data, chartType, options) => {
if (data[0].constructor === Object) data = toDataArray(data)
else if (typeof data[0] === "number")
data = [["", "Value"], ...data.map((d, i) => [i + 1, d])]
const dom = div({class: "chart"})
setTimeout(() => new google.visualization[chartType](dom).draw(
google.visualization.arrayToDataTable(data), options))
return dom
}
const Tree = ({obj, indent = ""}) =>
(indent ? div : pre)(Object.entries(obj).map(([k, v]) => {
if (v?.constructor !== Object && !Array.isArray(v))
return div(indent + "🟰 ", van.tags.b(k + ": "), v)
const expanded = van.state(false)
let treeDom
const onclick = van.derive(() => expanded.val ?
() => (treeDom.remove(), expanded.val = !expanded.val) :
() => (treeDom = result.appendChild(Tree({obj: v, indent: indent + " "}),
expanded.val = !expanded.val)))
const result = div(
indent,
van.tags.a({onclick},
() => expanded.val ? "➖ " : "➕ ",
van.tags.b(k + ":"),
() => expanded.val ? "" : " {…}",
),
)
return result
}))
const ValueView = expr => {
try {
const value = eval(`(${expr})`)
if (value instanceof Element) return value
if (value?.constructor === Object || Array.isArray(value)) return Tree({obj: value})
return pre(String(value))
} catch (e) {
return pre({class: "err"}, e.message + "\n" + e.stack)
}
}
const Output = ({id, expr}) => div({class: "row"},
pre({class: "left"}, `Out[${id}]:`),
div({class: "break"}),
div({class: "right"}, ValueView(expr)),
)
const autoGrow = e => {
e.target.style.height = "5px"
e.target.style.height = (e.target.scrollHeight + 5) + "px"
}
const Input = ({id}) => {
const run = () => {
textareaDom.setAttribute("readonly", true)
runDom.disabled = true
const newTextDom = van.add(textareaDom.closest(".console"), Output({id, expr: textareaDom.value}))
.appendChild(Input({id: id + 1}))
.querySelector("textarea")
newTextDom.focus()
setTimeout(() => newTextDom.scrollIntoView(), 10)
}
const runDom = button({class: "run", onclick: run}, "Run")
const onkeydown = async e => {
if ((e.metaKey || e.ctrlKey) && e.key === "Enter") {
e.preventDefault()
run()
}
}
const textareaDom = textarea({id, type: "text", onkeydown, oninput: autoGrow,
rows: 1, placeholder: 'Enter JS expression here:'})
return div({class: "row"},
pre({class: "left"}, `In[${id}]:`), runDom, div({class: "break"}),
div({class: "right"}, textareaDom),
)
}
const Console = () => div({class: "console"}, Input({id: 1}))
</code></pre><p><b>Demo:</b></p><p id="demo-js-console"></p><p><a href="https://jsfiddle.net/gh/get/library/pure/vanjs-org/vanjs-org.github.io/tree/master/jsfiddle/demo/js-console">Try on jsfiddle</a></p><p>You can also try out the JavaScript console in <a href="/code/console.html" class="w3-hover-opacity">this standalone page</a>.</p><h2 class="w3-xxlarge w3-text-red" id="an-improved-unix-terminal"><a class="self-link" href="#an-improved-unix-terminal">An Improved Unix Terminal</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Next up is a web-based Unix terminal that connects to your local computer, with notable improvements, all under 300 lines of code. This is to demonstrate that, with <b>VanJS</b>, we can easily provide great extension to commandline utilities with fancy GUI by leveraging all available HTML elements. The program is heavily tested in macOS, and should in theory works in Linux, or in any environment that has <code class="symbol"><a href="https://en.wikipedia.org/wiki/Bourne_shell" class="w3-hover-opacity">/bin/sh</a></code>.</p><p>See <a href="https://github.com/vanjs-org/van/tree/main/demo/terminal" class="w3-hover-opacity">github.com/vanjs-org/van/tree/main/demo/terminal</a> for the app (<a href="https://codesandbox.io/p/sandbox/github/vanjs-org/van/tree/main/demo/terminal" class="w3-hover-opacity">preview</a>).</p><h2 class="w3-xxlarge w3-text-red" id="community-examples"><a class="self-link" href="#community-examples">Community Examples</a></h2><hr style="width:50px;border:5px solid red" class="w3-round"><p>Besides the official <b>VanJS</b> examples, there are also sample apps from the great <b>VanJS</b> community. Below is a curated list (contact <a href="mailto:tao@vanjs.org" class="w3-hover-opacity">tao@vanjs.org</a> to add yours):</p><table><thead><tr><th>Author</th><th>Project</th><th>Preview</th></tr></thead><tbody><tr><td><a href="https://github.com/yahia-berashish" class="w3-hover-opacity">Yahia Berashish</a></td><td><a href="https://github.com/vitejs/awesome-vite#vanjs" class="w3-hover-opacity"><b>VanJS</b> JavaScript and TypeScript Vite Template</a></td><td><a href="https://codesandbox.io/p/sandbox/github/yahia-berashish/vite-vanjs-ts/tree/main" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/artydev" class="w3-hover-opacity">artydev</a></td><td><a href="https://dev.to/artydev/series/23075" class="w3-hover-opacity"><b>VanJS</b> Series</a></td><td></td></tr><tr><td><a href="https://github.com/barrymun" class="w3-hover-opacity">barrymun</a></td><td><a href="https://github.com/barrymun/division-game" class="w3-hover-opacity">Division Game</a></td><td><a href="http://barrymun.vanjs-division-game.surge.sh/" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/enpitsuLin" class="w3-hover-opacity">enpitsuLin</a></td><td><a href="https://github.com/enpitsuLin/vanjs-todomvc" class="w3-hover-opacity">TODO App</a></td><td><a href="https://codesandbox.io/p/sandbox/github/enpitsuLin/vanjs-todomvc/tree/master?file=%2Fsrc%2Fmain.ts%3A8%2C1" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/kwameopareasiedu" class="w3-hover-opacity">Kwame Opare Asiedu</a></td><td><a href="https://github.com/kwameopareasiedu/vanjs-todo" class="w3-hover-opacity">TODO App</a> with routing and authentication</td><td><a href="https://kwameopareasiedu.github.io/vanjs-todo/" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/CodeByZack" class="w3-hover-opacity">董凯</a></td><td><a href="https://github.com/CodeByZack/local-share" class="w3-hover-opacity">Local Share</a> - A tool for transferring files over LAN, using the WebRTC tech</td><td><a href="https://share.zackdk.com/" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/csm-kb" class="w3-hover-opacity">Kane</a></td><td><a href="https://github.com/csm-kb/vanjs-chartjs-example" class="w3-hover-opacity"><b>VanJS</b> Chart.js graph render</a></td><td><a href="https://codesandbox.io/p/devbox/github/csm-kb/vanjs-chartjs-example/tree/main/?file=%2Fsrc%2Fmain.ts" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/ndrean" class="w3-hover-opacity">Neven DREAN</a></td><td><a href="https://github.com/ndrean/vanjs-dialog-modal" class="w3-hover-opacity">Modal Component & Routing with <b>VanJS</b></a></td><td><a href="https://githubbox.com/ndrean/vanjs-dialog-modal" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/b-rad-c" class="w3-hover-opacity">b rad c</a></td><td><a href="https://github.com/vanjs-org/van/tree/main/addons/van_cone/examples/spa-app" class="w3-hover-opacity"><b>VanJS</b> SPA Template</a></td><td><a href="https://codesandbox.io/p/devbox/github/vanjs-org/van/tree/main/addons/van_cone/examples/spa-app" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/SirenkoVladd" class="w3-hover-opacity">Vlad Sirenko</a></td><td><a href="https://github.com/sirenkovladd/vanjs-leaflet-example" class="w3-hover-opacity"><b>VanJS</b> with Leaflet</a></td><td><a href="https://codesandbox.io/p/devbox/github/sirenkovladd/vanjs-leaflet-example/tree/main/?file=%2Fsrc%2Fmain.js" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/kangaroolab" class="w3-hover-opacity">kangaroolab</a></td><td><a href="https://github.com/kangaroolab/tippy" class="w3-hover-opacity">tippy: a local first note app</a></td><td><a href="https://kangaroolab.github.io/tippy/" class="w3-hover-opacity">link</a></td></tr><tr><td><a href="https://github.com/FredericHeem" class="w3-hover-opacity">FredericHeem</a></td><td><a href="https://github.com/FredericHeem/van-kit" class="w3-hover-opacity">Multi-Page App Starter Kit under 5kB</a></td><td></td></tr><tr><td><a href="https://github.com/FredericHeem" class="w3-hover-opacity">FredericHeem</a></td><td><a href="https://github.com/FredericHeem/van-playground" class="w3-hover-opacity"><b>VanJS</b> Playground with Vite</a></td><td></td></tr></tbody></table></div>
<aside id="toc"><ul><li><a href="#hello-world" class="w3-hover-opacity">Hello World!</a></li><li><a href="#dom-composition-and-manipulation" class="w3-hover-opacity">DOM Composition and Manipulation</a></li><li><a href="#counter" class="w3-hover-opacity">Counter</a></li><li><a href="#stopwatch" class="w3-hover-opacity">Stopwatch</a></li><li><a href="#blog" class="w3-hover-opacity">Blog</a></li><li><a href="#list" class="w3-hover-opacity">List</a></li><li><a href="#todo-list" class="w3-hover-opacity">TODO List</a></li><li><a href="#todo-app" class="w3-hover-opacity">A Fully Reactive TODO App</a></li><li><a href="#game" class="w3-hover-opacity">Fun Game: Emojis Pops</a></li><li><a href="#code-browser" class="w3-hover-opacity">SPA w/ Client-Side Routing: Code Browser</a></li><li><a href="#stargazers" class="w3-hover-opacity">Stargazers</a></li><li><a href="#epoch-timestamp-converter" class="w3-hover-opacity">Epoch Timestamp Converter</a></li><li><a href="#keyboard-event-inspector" class="w3-hover-opacity">Keyboard Event Inspector</a></li><li><a href="#diff" class="w3-hover-opacity">Diff</a></li><li><a href="#calculator" class="w3-hover-opacity">Calculator</a></li><li><a href="#table-viewer" class="w3-hover-opacity">Table-View Example: JSON/CSV Table Viewer</a></li><li><a href="#package-lock-inspector" class="w3-hover-opacity">package-lock.json Inspector</a></li><li><a href="#json-inspector" class="w3-hover-opacity">Tree-View Example: JSON Inspector</a></li><li><a href="#auto-complete" class="w3-hover-opacity">Textarea with Autocomplete</a></li><li><a href="#html-md-to-vanjs-code-converter" class="w3-hover-opacity">HTML/MD to VanJS Code Converter</a></li><li><a href="#jupyter-like-javascript-console" class="w3-hover-opacity">Jupyter-like JavaScript Console</a></li><li><a href="#an-improved-unix-terminal" class="w3-hover-opacity">An Improved Unix Terminal</a></li><li><a href="#community-examples" class="w3-hover-opacity">Community Examples</a></li></ul></aside>
</div>
</div>
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if (eBottom > tocBottom) tocDom.scrollTop += eBottom - tocBottom
else if (eTop < tocTop) tocDom.scrollTop -= tocTop - eTop
} else
e.classList.remove("current-heading")
}
trackToc()
document.addEventListener("scroll", trackToc)
addEventListener("resize", trackToc)
const copy = e => {
const file = e.previousElementSibling.innerText
const importLine = file.includes("nomodule") ?
`<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/vanjs-org/van/public/${file}"><\/script>` :
`import van from "https://cdn.jsdelivr.net/gh/vanjs-org/van/public/${file}"`
navigator.clipboard.writeText(importLine)
.then(() => e.querySelector(".tooltip").innerText = "Copied")
.catch(() => e.querySelector(".tooltip").innerText = "Copy failed")
}
const resetTooltip = e => e.querySelector(".tooltip").innerText = "Copy import line"
</script>
<script src="https://guru-widget.pages.dev/guru_widget.latest.min.js" data-text="Ask AI" data-link="https://gurubase.io/g/vanjs" data-bg-color="rgba(244, 67, 54, 0.3)" data-icon-url="/ask_ai.svg" data-font-color="#ffffff" data-margins="{"bottom": "1rem", "left": "1430px", "right": "unset"}">
</script>
<!-- Place this tag in your head or just before your close body tag. -->
<script async defer src="https://buttons.github.io/buttons.js"></script>
<link rel="prefetch" href="/code/prism-v1.js" as="script"><link rel="prefetch" href="https://www.gstatic.com/charts/loader.js" as="script"><link rel="prefetch" href="/code/diff.min.js" as="script"><link rel="prefetch" href="/code/van-1.5.2.nomodule.min.js" as="script"><link rel="prefetch" href="/code/van-x-0.6.1.nomodule.min.js" as="script"></body></html>