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Array.unshift( ) insert elements at the beginning of an array


JavaScript 1.2; JScript 5.5; ECMAScript v3


array.unshift(value, ...) 


value, ...

One or more values that are to be inserted at the start of array.


The new length of the array.


unshift( ) inserts its arguments at the beginning of array, shifting the existing elements to higher indexes to make room. The first argument to shift( ) becomes the new element 0 of the array, the second argument, if any, becomes the new element 1, and so on. Note that unshift( ) does not create a new array; it modifies array directly.


unshift( ) is often used in conjunction with shift( ). For example:

var a = [];             // a:[]

a.unshift(1);           // a:[1]          Returns: 1

a.unshift(22);          // a:[22,1]       Returns: 2

a.shift(  );            // a:[1]          Returns: 22

a.unshift(33,[4,5]);    // a:[33,[4,5],1] Returns: 3 

See Also

Array.shift( )

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