Recipe 5.5. Inserting Elements in the Middle of an Array

Problem

You want to insert elements in the middle of an array.

Solution

Use the splice( ) method.

Discussion

You can use the splice( ) method to insert elements as well as delete them. Values passed to the splice( ) method after the first and second parameters are inserted into the array at the index specified by the start parameter; all existing elements following that index are shifted up to accommodate the inserted values. If 0 is passed to the splice( ) method for the deleteCount parameter, no elements are deleted, but the new values are inserted:

var letters:Array = ["a", "b", "c", "d"];
     
// Insert three string values ("one", "two", and "three")
// starting at index 1.
letters.splice(1, 0, "r", "s", "t");
     
// letters now contains seven elements:
// "a", "r", "s", "t", "b", "c", and "d".
for (var i:int = 0; i < letters.length; i++) {
    trace(letters[i]);
}

You can also delete elements and insert new elements at the same time:

var letters:Array = ["a", "b", "c", "d"];
     
// Remove two elements and insert three more 
// into letters starting at index 1.
letters.splice(1, 2, "r", "s", "t");
     
// myArray now contains five elements:
// "a", "r", "s", "t", and "d".
for (var i:int = 0; i < letters.length; i++) {
    trace(letters[i]);
}