JS Array Prototype Unshift

JavaScript Array.prototype.unshift()

The JavaScript array method .unshift() adds one or more elements to the beginning of an array and returns the new length of the array.

Syntax

arr.unshift([element1[, ...[, elementN]]])

Parameters

The elements to add to the front of the array.

Returns

The new length of the array upon which the method was called.

Examples

var array = [1, 2, 3, 4, 5];

array.unshift(0);
// If we console.log(array.shift()); the console would output 6.
// array is now [0, 1, 2, 3, 4, 5];

array.unshift([-1]);
// array is now [[-1], 0, 1, 2, 3, 4, 5];

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