refactor: Finalize mount/unmount/update

src/components/code-editor/index.jsx

@@ -1,7 +1,7 @@
-import { useState, useRef, useEffect } from 'preact/hooks';
+import { useRef, useEffect } from 'preact/hooks';
 import { EditorView } from 'codemirror';
 import { lineNumbers, keymap, highlightActiveLineGutter, highlightActiveLine } from '@codemirror/view';
-import { EditorState } from '@codemirror/state';
+import { EditorState, Transaction } from '@codemirror/state';
 import { defaultKeymap, history, historyKeymap, indentWithTab } from '@codemirror/commands';
 import { javascript } from '@codemirror/lang-javascript';
 import { syntaxHighlighting, HighlightStyle, indentUnit, bracketMatching } from '@codemirror/language';
@@ -26,16 +26,34 @@ const highlightStyle = HighlightStyle.define([
 	{ tag: tags.invalid, class: 'cm-invalid' }
 ]);
 
+/**
+ * @param {object} props
+ * @param {string} props.value
+ * @param {(value: string) => void} props.onInput
+ * @param {string} props.slug
+ * @param {string} [props.class]
+ */
 export default function CodeEditor(props) {
 	const editorParent = useRef(null);
+	/** @type {{ current: EditorView | null }} */
 	const editor = useRef(null);
-	// eslint-disable-next-line no-unused-vars
-	const [_, setEditor] = useState(null);
+
+	const routeHasChanged = useRef(false);
+
+	useEffect(() => {
+		if (props.slug || !editor.current) routeHasChanged.current = true;
+	}, [props.slug]);
 
 	useEffect(() => {
-		console.log('editor code:\n', props.value);
-		if (editor.current && !props.baseExampleSlug) return;
-		if (editor.current) editor.current.destroy();
+		if (routeHasChanged.current === false) return;
+		routeHasChanged.current = false;
+
+		if (editor.current) {
+			editor.current.dispatch({
+				changes: { from: 0, to: editor.current.state.doc.length, insert: props.value }
+			});
+			return;
+		}
 
 		const theme = EditorView.theme({}, { dark: true });
 
@@ -54,8 +72,9 @@ export default function CodeEditor(props) {
 				keymap.of([indentWithTab, ...defaultKeymap, ...historyKeymap]),
 				[theme, syntaxHighlighting(highlightStyle, { fallback: true })],
 				EditorView.updateListener.of(update => {
-					if (update.docChanged) {
-						if (props.onInput) props.onInput({ value: update.state.doc.toString() });
+					// Ignores changes from swapping out the editor code programmatically
+					if (isViewUpdateFromUserInput(update)) {
+						props.onInput(update.state.doc.toString());
 					}
 				})
 			]
@@ -65,16 +84,23 @@ export default function CodeEditor(props) {
 			state,
 			parent: editorParent.current
 		});
-
-		setEditor(editor.current);
-	}, [props.baseExampleSlug]);
+	}, [props.value]);
 
 	useEffect(() => (
 		() => {
-			editor.current.destroy();
-			setEditor(null);
+			if (editor.current) editor.current.destroy();
 		}
 	), []);
 
 	return <div ref={editorParent} class={cx(style.codeEditor, props.class)} />;
 }
+
+/** @param {import('@codemirror/view').ViewUpdate} viewUpdate */
+function isViewUpdateFromUserInput(viewUpdate) {
+	if (viewUpdate.docChanged) {
+		for (const transaction of viewUpdate.transactions) {
+			if (transaction.annotation(Transaction.userEvent)) return true;
+		}
+	}
+	return false;
+}

src/components/controllers/repl/index.jsx

@@ -2,8 +2,8 @@ import { useState, useEffect } from 'preact/hooks';
 import { useLocation, useRoute } from 'preact-iso';
 import { Splitter } from '../../splitter';
 import { textToBase64 } from './query-encode.js';
-import { EXAMPLES, fetchExample } from './examples';
 import { ErrorOverlay } from './error-overlay';
+import { EXAMPLES, fetchExample } from './examples';
 import { useStoredValue } from '../../../lib/localstorage';
 import { useResource } from '../../../lib/use-resource';
 import { parseStackTrace } from './errors';
@@ -23,12 +23,11 @@ export function Repl({ code }) {
 	const [error, setError] = useState(null);
 	const [copied, setCopied] = useState(false);
 
-	// TODO: CodeMirror v5 cannot load in Node, and loading only the runner
-	// causes some bad jumping/pop-in. For the moment, this is the best option
+	// TODO: Needs some work for prerendering to not cause pop-in
 	if (typeof window === 'undefined') return null;
 
 	/**
-	 * @type {{ Runner: import('../repl/runner').default, CodeEditor: import('../../code-editor').default }}
+	 * @type {{ Runner: import('./runner').default, CodeEditor: import('../../code-editor').default }}
 	 */
 	const { Runner, CodeEditor } = useResource(() => Promise.all([
 		import('../../code-editor'),
@@ -143,8 +142,7 @@ export function Repl({ code }) {
 					<CodeEditor
 						class={style.code}
 						value={editorCode}
-						baseExampleSlug={exampleSlug}
-						error={error}
+						slug={query.example}
 						onInput={onEditorInput}
 					/>
 				</Splitter>

src/components/controllers/tutorial/index.jsx

@@ -59,8 +59,7 @@ export function Tutorial({ html, meta }) {
 	const hasCode = meta.code !== false;
 	const showCode = showCodeOverride && hasCode;
 
-	// TODO: CodeMirror v5 cannot load in Node, and loading only the runner
-	// causes some bad jumping/pop-in. For the moment, this is the best option
+	// TODO: Needs some work for prerendering to not cause pop-in
 	if (typeof window === 'undefined') return null;
 
 	/**
@@ -184,15 +183,15 @@ export function Tutorial({ html, meta }) {
 								</>
 							}
 						>
-								<div class={style.codeWindow}>
-									<CodeEditor
-										class={style.code}
-										value={editorCode}
-										error={error}
-										onInput={setEditorCode}
-									/>
-								</div>
-							</Splitter>
+							<div class={style.codeWindow}>
+								<CodeEditor
+									class={style.code}
+									value={editorCode}
+									slug={path}
+									onInput={setEditorCode}
+								/>
+							</div>
+						</Splitter>
 					}
 				>
 					<div class={style.tutorialWindow} ref={content}>