Array

`Array.prototype.with`

Returns a new array with the element at the given index replaced with the given value, without modifying the original array

Syntax

JavaScript

array.with(index, value)

Parameters

Parameter	Type	Description
index	number	Zero-based index of the element to replace. Negative values count from end
value	T	The value to assign to the given index

Return Value

A new array with the element at the index replaced

Examples

Basic Usage

const arr = [1, 2, 3, 4, 5];
const updated = arr.with(2, 99);
console.log(updated); // [1, 2, 99, 4, 5]
console.log(arr); // [1, 2, 3, 4, 5] (unchanged)

Practical Example

const colors = ['red', 'green', 'blue'];
console.log(colors.with(-1, 'yellow')); // ['red', 'green', 'yellow']

Advanced Usage

const data = [10, 20, 30];
const chain = data.with(0, 11).with(2, 33);
console.log(chain); // [11, 20, 33]

Understanding Array.prototype.with

The Array.prototype.with method in JavaScript returns a new array with the element at the given index replaced with the given value, without modifying the original array. It belongs to the Array object and is one of the most widely used methods for working with array values in modern JavaScript and TypeScript applications.

The method signature is array.with(index, value). It accepts 2 parameters: index, value. When called, it returns a new array with the element at the index replaced. Understanding when and how to use with() helps you write more expressive, readable code.

Common use cases for Array.prototype.with include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like array-tosorted, array-toreversed, array-tospliced, enabling you to chain operations together for complex data manipulation pipelines.

Supported in Chrome 110+, Firefox 115+, Safari 16+, Edge 110+, and Node.js 20+.