JavaScript array methods

This is a categorized list of all native JavaScript array methods and properties grouped by the type of tasks they perform.

1. Mutating
   1. Add
   2. Remove
   3. Add / Remove
   4. Move
2. Accessing
   1. Add
   2. Remove
   3. Find
   4. Transforming
3. Iterating
4. Static properties & methods

Mutating

Add

push()
unshift()

Remove

pop()
shift()

Add / Remove

splice()
fill()

Move

copyWithin()
sort()
reverse()

Accessing

Add

concat()

Remove

slice()
filter()

Find

includes()
indexOf()
lastIndexOf()

Transforming

join()
toString()
toLocaleString()
toSource()

Iterating

map()
reduce()
reduceRight()
find()
findIndex()
forEach()
every()
some()
keys()
values()
entries()

Static properties & methods

.length
isArray()
from()
of()

Code Samples

push()

const a = [1, 2, 3];
const res = a.push(4, 5);
console.log(a, res);

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

unshift()

const a = [1, 2, 3];
const res = a.unshift(-1, 0);
console.log(a, res);

// [ -1, 0, 1, 2, 3 ]   5

pop()

const a = [1, 2, 3];
const res = a.pop();
console.log(a, res);

// [ 1, 2 ]   3

shift()

const a = [1, 2, 3];
const res = a.shift();
console.log(a, res);

// [ 2, 3 ]   1

splice()

const a = [1, 2, 3];
const res = a.splice(1, 1, 'two');
console.log(a, res);

// [ 1, "two", 3 ]   [ 2 ]

fill()

const a = [1, 2, 3];
const res = a.fill(4, 1);
console.log(a, res);

// [ 1, 4, 4 ]   [ 1, 4, 4 ]

copyWithin()

const a = [1, 2, 3];
const res = a.copyWithin(1, 0);
console.log(a, res);

// [ 1, 1, 2 ]   [ 1, 1, 2 ]

sort()

const a = [2, 1, 3];
const res = a.sort();
console.log(a, res);

// [ 1, 2, 3 ]   [ 1, 2, 3 ]

reverse()

const a = [1, 2, 3];
const res = a.reverse();
console.log(a, res);

// [ 3, 2, 1 ]   [ 3, 2, 1 ]

concat()

const a = [1, 2, 3];
const res = a.concat(4);
console.log(a, res);

// [ 1, 2, 3 ]   [ 1, 2, 3, 4 ]

slice()

const a = [1, 2, 3];
const res = a.slice(1, 2);
console.log(a, res);

// [ 1, 2, 3 ]   [ 2 ]

filter()

const a = [1, 2, 3];
const res = a.filter(num => num > 1);
console.log(a, res);

// [ 1, 2, 3 ]   [ 2, 3 ]

includes()

const a = [1, 2, 3];
const res = a.includes(4);
console.log(a, res);

// [ 1, 2, 3 ]   false

indexOf()

const a = [1, 2, 3];
const res = a.indexOf(3);
console.log(a, res);

// [ 1, 2, 3 ]   2

lastIndexOf()

const a = [1, 2, 1];
const res = a.lastIndexOf(1);
console.log(a, res);

// [ 1, 2, 3 ]   2

join()

const a = [1, 2, 3];
const res = a.join('-');
console.log(a, res);

// [ 1, 2, 3 ]   1-2-3

toString()

const a = [1, 2, 3];
const res = a.toString();
console.log(a, res);

// [ 1, 2, 3 ]   1,2,3

toLocaleString()

const a = [1, 2, 3];
const res = a.toLocaleString('en-GB', {
  style: 'currency',
  currency: 'GBP',
});
console.log(a, res);

// [ 1, 2, 3 ]   £1.00,£2.00,£3.00

toSource()

const a = [1, 2, 3];
const res = a.toSource();
console.log(a, res);

// [ 1, 2, 3 ]   "[1, 2, 3]"

map()

const a = [1, 2, 3];
const res = a.map(num => num * 10);
console.log(a, res);

// [ 1, 2, 3 ]   [ 10, 20, 30 ]

reduce()

const a = [1, 2, 3];
const res = a.reduce((acc, cur) => acc - cur);
console.log(a, res);

// [ 1, 2, 3 ]   -4

reduceRight()

const a = [1, 2, 3];
const res = a.reduceRight((acc, cur) => acc - cur);
console.log(a, res);

// [ 1, 2, 3 ]   0

find()

const a = [1, 2, 3];
const res = a.find(num => num % 2 === 0);
console.log(a, res);

// [ 1, 2, 3 ]   2

findIndex()

const a = [1, 2, 3];
const res = a.findIndex(num => num === 3);
console.log(a, res);

// [ 1, 2, 3 ]   2

forEach()

const a = [1, 2, 3];
a.forEach(num => console.log(num));

// 1
// 2
// 3

every()

const a = [1, 2, 3];
const res = a.every(num => num > 0);
console.log(a, res);

// [ 1, 2, 3 ]   true

some()

const a = [1, 2, 3];
const res = a.some(num => num > 2);
console.log(a, res);

// [ 1, 2, 3 ]   true

keys()

const a = [1, 2, 3];
const res = a.keys();
console.log(a, [...res]);

// [ 1, 2, 3 ]   [ 0, 1, 2 ]

values()

const a = [1, 2, 3];
const res = a.values();
console.log(a, res.next());

// [ 1, 2, 3 ]   { value: 1, done: false }

entries()

const a = [1, 2, 3];
const res = a.entries();
console.log(a, res.next());

// [ 1, 2, 3 ]   { value: [ 0, 1 ], done: false }

.length

const a = [1, 2, 3];
console.log(a.length);

// 3

Array.isArray

const a = [1, 2, 3];
const res = Array.isArray(a);
console.log(a, res);

// [ 1, 2, 3 ]   true

Array.from

const a = Array.from('word');
console.log(a);

// [ "w", "o", "r", "d" ]

Array.of

const a = Array.of(1, 2, 3);
console.log(a);

// [ 1, 2, 3 ]