Array Methods You Must Know

Array methods help us perform operations on arrays and modify or process their data more easily.

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push()

Adds an element at the end of the array.

const arr = [1, 2];

arr.push(3);

console.log(arr);

Output:

[1, 2, 3]

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pop()

Removes the last element from the array.

const arr = [1, 2, 3];

arr.pop();

console.log(arr);

Output:

[1, 2]

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unshift()

Adds an element at the beginning of the array.

const arr = [2, 3];

arr.unshift(1);

console.log(arr);

Output:

[1, 2, 3]

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shift()

Removes the first element from the array.

const arr = [1, 2, 3];

arr.shift();

console.log(arr);

Output:

[2, 3]

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map()

map() is used to iterate through an array and return a new array after performing some operation.

const arr = [1, 2, 3];

const doubled = arr.map((num, index, array) => {
  console.log(num, index, array);

  return num * 2;
});

console.log(doubled);

Output:

[2, 4, 6]

Parameters available inside map()

• num → current element

• index → current index

• array → original array

map() always returns a new array.

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filter()

filter() returns elements based on a condition.

const arr = [1, 2, 3, 4];

const even = arr.filter((num, index, array) => {
  console.log(num, index, array);

  return num % 2 === 0;
});

console.log(even);

Output:

[2, 4]

Parameters available inside filter()

• num → current element

• index → current index

• array → original array

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reduce()

reduce() loops through the array and reduces it into a single value.

const arr = [1, 2, 3, 4];

const sum = arr.reduce((acc, curr, index, array) => {
  console.log(acc, curr, index, array);

  return acc + curr;
}, 0);

console.log(sum);

Output:

10

Parameters available inside reduce()

• acc → accumulator (previous returned value)

• curr → current element

• index → current index

• array → original array

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forEach()

forEach() is used to iterate through an array.

const arr = [1, 2, 3];

arr.forEach((num, index, array) => {
  console.log(num, index, array);
});

Output:

1
2
3

Parameters available inside forEach()

• num → current element

• index → current index

• array → original array