Javascript [Electronic resources] : The Definitive Guide (4th Edition) نسخه متنی

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( )