Array.prototype.concat()

The Array.prototype.concat() method is used to merge two or more arrays into a new array.

The concat() method can also be used with non-array values, which will be added to the new array as individual elements.

If any of the arguments passed to the concat() method are themselves arrays, the elements of those arrays are added to the new array individually (i.e., the arrays are flattened).

The concat() method can be chained together with other array methods, allowing you to perform multiple operations on an array in a single line of code.

concat() method does not modify the original array. Instead, it returns a new array that contains the concatenated elements.

Syntax

array.concat(array1[, array2, ...])
array.concat(array1, array2, ..., arrayN)

Parameters

• array1, array2, ...arrayN: (required): The arrays to merge with the original array.

return value

A new array containing the elements of the original array and the concatenated arrays.

Examples

const array_a = [1, 2, 3];
const array_b_ = [4, 5, 6];
const newArray = array_a.concat(array_b);
// newArray is [1, 2, 3, 4, 5, 6]

const array1 = [1, 2, 3];
const array2 = [4, 5, 6];
const newArray = array1.concat(7, 8, 9, array2, [10, 11]);
// newArray is [1, 2, 3, 7, 8, 9, 4, 5, 6, 10, 11]

const array3 = ['a', 'b', 'c'];
const array4 = ['d', ['e', 'f']];
const array5 = array3.concat(array4);
// array5 is ['a', 'b', 'c', 'd', ['e', 'f']]

const array6 = [1, 2, 3];
const array7 = [4, 5, 6];
const newArray2 = array6.concat(array7).reverse();
// newArray2 is [6, 5, 4, 3, 2, 1]