Elyses Enchantments

In JavaScript, an array is a list-like structure with no fixed length which can hold any type of primitives or objects, even mixed types.

To create an array, add elements between square brackets []. To read from the array, put the index in square brackets [] after the identifier. The indices of an array start at zero.

For example:

const numbers = [1, 'two', 3, 'four'];
numbers[2];
// => 3

To retrieve the number of elements that are in an array, use the length property:

const numbers = [1, 'two', 3, 'four'];
numbers.length;
// => 4

To change an element in the array, you assign a value at the index:

const numbers = [1, 'two', 3, 'four'];
numbers[0] = 'one';
numbers;
// => ['one', 'two', 3, 'four']

Methods

Some of the methods that are available on every Array object can be used to add or remove from the array. Here are a few to consider when working on this exercise:

push

The push() method adds one or more elements to the end of an array and returns the new length of the array.¹

const numbers = [1, 'two', 3, 'four'];
numbers.push(5); // => 5
numbers;
// => [1, 'two', 3, 'four', 5]

pop

The pop() method removes the last element from an array and returns that element. This method changes the length of the array.²

const numbers = [1, 'two', 3, 'four'];
numbers.pop(); // => four
numbers;
// => [1, 'two', 3]

shift

The shift() method removes the first element from an array and returns that removed element. This method changes the length of the array.³

const numbers = [1, 'two', 3, 'four'];
numbers.shift(); // => 1
numbers;
// => ['two', 3, 'four']

unshift

The unshift() method adds one or more elements to the beginning of an array and returns the new length of the array.⁴

const numbers = [1, 'two', 3, 'four'];
numbers.unshift('one'); // => 5
numbers;
// => ['one', 1, 'two', 3, 'four']

splice

The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place. This method returns an array containing the deleted elements.⁵

const numbers = [1, 'two', 3, 'four'];
numbers.splice(2, 1, 'one'); // => [3]
numbers;
// => [1, 'two', 'one', 'four']

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1. push, MDN. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push (referenced September 29, 2021) ↩

2. pop, MDN. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/pop (referenced September 29, 2021) ↩

3. shift, MDN. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/shift (referenced September 29, 2021) ↩

4. unshift, MDN. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/unshift (referenced September 29, 2021) ↩

5. splice, MDN. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice (referenced September 29, 2021) ↩