Array.unshift( ) |
insert elements at the beginning of an
array |
Availability
JavaScript 1.2; JScript 5.5; ECMAScript v3
Synopsis
array.unshift(value, ...)
Arguments
- value, ...
-
One or more values that are to be inserted at the start of
array.
Returns
The new length of the array.
Description
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.
Example
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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