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Exercise Set 1: Basics

This set of exercices requires you to know about

  • basic data types (boolean, number, string)
  • how to call a function
  • how to create a more complex expression
    • by nesting function calls
    • by combining expressions with operators
  • the basics of variable bindings (using let)

The exercices might introduce new concepts, but I'll try to make that explicit.

Exercise 1

1a) Adding different data types

In class we have seen, how you can add numbers like this:

> 10+20
30

or to concatenate strings, like this:

> "mad" + "hatter"
'madhatter'

But what if you add a number and a string (like "Lucky Number " + 7?). What does "20"+24 do? Try it! Can you explain the behavior?

Hint: Read the Eloquent JS section on type conversion.

1b) Asking for different data types with readline-sync

In class we have seen, how to ask a user for their name, like this:

let readlineSync = require("readline-sync");
let name = readlineSync.question("What's your name?");
console.log("Hello, " + name + ", welcome to my program!");

Try to ask the user for their favorite number instead and print it!

  • The program should ask "What's your favorite number?"
  • Let's say the user enters 7.
  • Print it back to them: "Thanks for letting me know that your favorite number is 7".

Now add 3 to the number and give it back as well:

  • "Thanks for letting me know your favorite number. If we add 3, we get: 10"

Hints

If you try this, you might get the problem as shown in exercise 1a, that there's an automatic type conversion happening. Your output might look like: "Thanks for letting me know your favorite number. If we add 3, we get: 73". That's okay, and a good first step towards the solution! How to solve it though?

For this use-case there's another method in the readline-sync package. It's called questionInt. Here's an example:

let readlineSync = require("readline-sync");
let name = readlineSync.question("What's your name?");
let favoriteNumber = readlineSync.questionInt("What's your favorite number?");
console.log("Hello, " + name + ", welcome to my program!");
console.log("Your favorite number is: " + favoriteNumber);
// and then you need to do your calculations, like adding something with the number here :)

For example, my program runs like this:

% node hw_ex01b.js
What's your name? Moritz
What's your favorite number? 7
Hello, Moritz, welcome to my program!
Thanks for letting me know your favorite number.
Your favorite number is: 7
If we double it, we get: 14.
If we add three, we get: 10.
If you do both, you'll get: 17.
Or the other way around (add, then double): 20.

Now try it yourself!

Another hint: You might need to use parentheses to prevent type conversion. For example console.log("Some text " + favoriteNumber + 3) does something else than console.log("Some text " + (favoriteNumber + 3))

Exercise 2: Printing a Car to your terminal

Choose an Ascii art from the website https://www.asciiart.eu/.
Output it to the console.

For example a car:

       _______
       //  ||\ \
 _____//___||_\ \___
 )  _          _    \
 |_/ \________/ \___|
___\_/________\_/______

So when you run you program like this: node hw_ex02.js, you should see the corresponding output.

Hints

  1. This is not a complicated exercise, don't overthink it :) The idea is to teach you about a concept called "whitespace" in strings.
  2. What happens if you add spaces to your string to print, such as console.log(" spaced out ")
  3. With your knowledge it's easiest to solve this exercise by calling console.log multiple times.
  4. Advanced approach: It's possible to do it in one line of code (but tricky to get the alignment right) by using something called a newline character.
  5. Alternative solution that requires extra knowledge: Do some research about Template Literals in JavaScript.