Javascript Arrays

Array Methods

Array ForEach

const numbers = [1, 2, 3, 4, 5]

numbers.forEach(number => console.log(number));

$ 1
$ 2
$ 3
$ 4
$ 5

Acts on each member of the array.

Array Map

const numbers = [1, 2, 3, 4, 5];

const newNumber = numbers.map((number) => number + 1);

console.log(newNumber);

Returns a new array.

Array Filter

const numbers = [1, 2, 3, 4, 5]

const filteredNumbers = numbers.filter(number => number < 3);

console.log(filteredNumbers)

$ [1, 2]

Returns a new array

Array Find

Array Includes

const numbers = [1, 2, 3, 4, 5]

numbers.includes(2);

$ true

Returns a boolean

Array Sort

const numbers = [1, 2, 3, 4, 5];

const sortedArray = numbers.sort((a, b) => b - a);

console.log(sortedArray);

$ [5, 4, 3, 2, 1] // <== b - a sorts descending, a - b sorts ascending

Array Some and Every

const numbers = [1, 2, 3, 4, 5];

const some = numbers.some((number) => number < 3);
const every = numbers.every((number) => number < 3);

console.log(some);
console.log(every);

$ true
$ false

Array Reduce

const numbers = [1, 2, 3, 4, 5];

const sum = numbers.reduce((accumulator, number) => accumulator + number);

console.log(sum);

Performs an action on each round and stores the value in the accumulator. The accumulator starts with the value of the first member of the array.

Array Reverse

const numbers = [1, 2, 3, 4, 5];

const reversedArray = numbers.reverse();

console.log(reversedArray);

$ [5, 4, 3, 2, 1]

Array Concat

const numbers1 = [1, 2, 3, 4, 5];
const numbers2 = [6, 7, 8, 9, 10];

const concatArr = numbers1.concat(numbers2);

console.log(concatArr);

$ [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

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