CodeLab

Learn by reading real code

Examples and small projects from our lessons. Read the explanation, copy or download the code, run front-end examples live, and experiment in the Playground.

8Examples

2Projects

6Languages

6Live previews

playground.js

const learner = { name: 'You', level: 'beginner' };

function practise(topic) {
  console.log(`${learner.name} is learning ${topic}!`);
  learner.level = 'getting better';
}

['HTML', 'CSS', 'JavaScript'].forEach(practise);

Open the PlaygroundWrite HTML, CSS & JavaScript and see it run

Results 1

Any level Beginner Intermediate Advanced

Arrays Clear all

script.js

const scores = [45, 72, 88, 39, 91, 66];

// map: a new array, one result per item
const percentages = scores.map(score => score + '%');
console.log('As percentages:', percentages);

// filter: only the items that pass a test

Intermediate Live preview

Array methods: map, filter and reduce

Transform, select and total a list of quiz scores without a single for loop.

JavaScript

13 lines View snippet