lesson10.md

Basic Frontend - Spring 2024

Lesson 10, Thursday, 2024-04-18

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Recap: getElementById

• What is getElementById?
• When do we use it?
• What does it return?
• How do we find out which properties we can set/get?

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MAJOR TWIST

string, boolean, number, undefined and null are primitive data types

object is a non-primitive data type

However - even primitive data types can have properties in JavaScript.

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Example

let greeting = "Hello";
let price = 1/3;

greeting.replace('e', 'a'); // returns "Hallo"
price.toFixed(2)            // returns "0.33"

We can use the toFixed() method on numbers to round to get a string with fewer digits after the decimal point.

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Project

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Option 1

Let's write a number guessing game! Let the computer guess a secret number between 1 and 100:

let secretNumber = Math.floor(Math.random() * 100) + 1;

Create a game web page where your user can guess any number between 1 and 100. The game must tell the user whether they guessed too high or too low. Once the user guesses the secret number, the game is over.

BONUS: Also print the user's previous guesses

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Option 2

Let's write a web shop! Choose two products of your liking and let the user select the amount they want to buy. Compute the total cost.

BONUS: Also offer express shipping for a small extra fee.

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Sample solutions

guessing game

web store