3 · Work with collections · 8 MIN

Keep an ordered list

Arrays store values in order, starting at index zero.

Use array[0] for the first item and array.length for the number of items. Reading a position that does not exist gives undefined. An empty list needs deliberate handling. Arrays are useful when you have several values of the same kind.

A row of numbered lockers starts at locker 0 in JavaScript.

Read the example

const names = ["Ada", "Lin", "Grace"];
console.log(names[0]);
console.log(names.length);

Ada
3

Your challenge

Return the first item of the input array. Return null if the array is empty.

Common trap

The last index is length - 1, not length.