JavaScript: The Definitive Guide, Fourth Edition

Name

Array.splice( ) — insert, remove, or replace array elements

Availability

JavaScript 1.2; JScript 5.5; ECMAScript v3

Synopsis

                  array.splice(start, deleteCount, value, ...)

Arguments

start

The array element at which the insertion and/or deletion is to begin.

deleteCount

The number of elements, starting with and including start, to be deleted from array. This argument is optional; if not specified, splice( ) deletes all elements from start to the end of the array.

value, ...

Zero or more values to be inserted into array, beginning at the index specified by start.

Returns

An array containing the elements, if any, deleted from array. Note, however, that due to a bug, the return value is not always an array in the Netscape implementation of JavaScript 1.2.

Description

splice( ) deletes zero or more array elements starting with and including the element start and replaces them with zero or more values specified in the argument list. Array elements that appear after the insertion or deletion are moved as necessary so that they remain contiguous with the rest of the array. Note that, unlike the similarly named slice( ), splice( ) modifies array directly.

Example

The operation of splice( ) is most easily understood through an example:

var a = [1,2,3,4,5,6,7,8] a.splice(4); // Returns [5,6,7,8]; a is [1,2,3,4] a.splice(1,2); // Returns [2,3]; a is [1,4] a.splice(1,1); // Netscape/JavaScript 1.2 returns 4 instead of [4] a.splice(1,0,2,3); // Netscape/JavaScript 1.2 returns undefined instead ...