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    Array.prototype.unshift()

    Summary

    The unshift() method 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

    elementN
    The elements to add to the front of the array.

    Returns

    The new length property of the object upon which the method was called.

    Description

    The unshift method inserts the given values to the beginning of an array-like object.

    unshift is intentionally generic; this method can be called or applied to objects resembling arrays. Objects which do not contain a length property reflecting the last in a series of consecutive, zero-based numerical properties may not behave in any meaningful manner.

    Examples

    var arr = [1, 2];
    
    arr.unshift(0); // result of call is 3, the new array length
    // arr is [0, 1, 2]
    
    arr.unshift(-2, -1); // = 5
    // arr is [-2, -1, 0, 1, 2]
    
    arr.unshift([-3]);
    // arr is [[-3], -2, -1, 0, 1, 2]
    

    Specifications

    Specification Status Comment
    ECMAScript 3rd Edition Standard Initial definition. Implemented in JavaScript 1.2.
    ECMAScript 5.1 (ECMA-262)
    The definition of 'Array.prototype.unshift' in that specification.
    Standard  
    ECMAScript 6 (ECMA-262)
    The definition of 'Array.prototype.unshift' in that specification.
    Draft  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support 1.0 1.0 (1.7 or earlier) 5.5 (Yes) (Yes)
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

    See also

    Document Tags and Contributors

    Last updated by: Mingun,
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