JavaScript 1.2; JScript 5.5; ECMAScript v3
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