Array.prototype.splice()

splice(start[, deleteCount[, item1, item2, ...]])

The splice() method changes an array by removing, replacing, or adding elements in place. It modifies the original array and returns an array containing the deleted elements (or an empty array if nothing was removed).

Syntax

array.splice(start)
array.splice(start, deleteCount)
array.splice(start, deleteCount, item1)
array.splice(start, deleteCount, item1, item2, /* ... */)

Parameters

Parameter	Type	Default	Description
start	number	—	Index where to start changing the array. Negative counts from the end.
deleteCount	number	Infinity	Number of elements to remove. If omitted, removes all elements from start to the end.
item1, item2, ...	any	—	Elements to add to the array at the start position.

Examples

Removing elements

const fruits = ['apple', 'banana', 'cherry', 'date'];
const removed = fruits.splice(1, 2);

console.log(fruits);
// ['apple', 'date']

console.log(removed);
// ['banana', 'cherry']

Adding elements

const colors = ['red', 'blue'];
colors.splice(1, 0, 'green', 'yellow');

console.log(colors);
// ['red', 'green', 'yellow', 'blue']

Replacing elements

const numbers = [1, 2, 3, 4, 5];
const removed = numbers.splice(2, 2, 30, 40);

console.log(numbers);
// [1, 2, 30, 40, 5]

console.log(removed);
// [3, 4]

Using negative index

const items = ['a', 'b', 'c', 'd', 'e'];
items.splice(-2, 1, 'X');

console.log(items);
// ['a', 'b', 'c', 'X', 'e']

Using toSpliced() (Immutable)

The toSpliced() method (ES2023) works identically but returns a new array without modifying the original:

const original = [1, 2, 3, 4, 5];
const modified = original.toSpliced(1, 2, 99);

console.log(original);
// [1, 2, 3, 4, 5] — unchanged

console.log(modified);
// [1, 99, 4, 5]

Common Patterns

Removing first element

const arr = [1, 2, 3];
arr.shift(); // slower, reindexes
// Better:
arr.splice(0, 1);

Removing last element

const arr = [1, 2, 3];
arr.pop(); // faster for just removing
arr.splice(-1, 1); // equivalent but slower

Insert at specific position

function insertAt(array, index, ...items) {
  array.splice(index, 0, ...items);
}

const nums = [1, 2, 5];
insertAt(nums, 2, 3, 4);
console.log(nums); // [1, 2, 3, 4, 5]

See Also

• array::filter
• array::unshift