JavaScript Array prototype splice

This method changes array's content by removing existing elements and/or adding new elements.

Syntax

array.splice(start, deleteCount[, item1[, item2[, ...]]])

Parameters

Parameter	Description	Necessity
start	Index at which to start changing the array.	Required
deleteCount	An integer indicating the number of old array elements to remove. If deleteCount is 0, no elements are removed. In this case, you should specify at least one new element.	Required
itemN	The element to add to the array. If you don't specify any elements, splice() will only remove elements from the array.	Optional

MDN link | MSDN link

Returns

An array containing the deleted elements. If only one element is removed, an array of one element is returned. If no elements are removed, an empty array is returned.

Examples

var arr = new Array("4", "11", "2", "10", "3", "1");
arr.splice(2, 2, "21", "31");
document.write(arr);

// Output: 4,11,21,31,3,1

var myFish = ['angel', 'clown', 'mandarin', 'surgeon'];

// removes 0 elements from index 2, and inserts 'drum'
var removed = myFish.splice(2, 0, 'drum');
// myFish is ['angel', 'clown', 'drum', 'mandarin', 'surgeon']
// removed is [], no elements removed

// removes 1 element from index 3
removed = myFish.splice(3, 1);
// myFish is ['angel', 'clown', 'drum', 'surgeon']
// removed is ['mandarin']