Description

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Beginner · 8 min

Work with arrays

Store an ordered collection and access or add items.

Read an item

An array stores an ordered list inside square brackets. Indexing starts at 0. The length property reports the number of items.

const cities = ["Rome", "Oslo", "Lima"];
console.log(cities[0]);
console.log(cities.length);

Output

Rome
3

Add an item

push() adds an item at the end. A const binding cannot be reassigned, but the contents of an array stored in it can change. join() combines the items into a string.

const tasks = ["Read", "Practice"];
tasks.push("Review");
console.log(tasks.join(", "));

Output

Read, Practice, Review

Put it into practice

  1. Predict the output of each example before running it.
  2. Complete the coding task, then try the practice questions.

Try it yourself

Code runs on this device. When you are signed in, drafts sync to your account.

Extend a shopping list

Add "Milk" to items with push(), then display the list joined with ", ".

Practice