The Art of Development: JavaScript Associative Array

Sunday, August 21, 2011

JavaScript Associative Array

Although an associative array doesn’t technically exist in JavaScript it can be achieved via

        1: var myArray = new Array();

       2: myArray["index1"] = "Value1";

       3: myArray["index2"] = "Value2";

This is all fine and dandy till you realise that the length property will always return zero ( 0 )

       1: //always displays zero

       2: alert(myArray.length);

This can be highly annoying considering the fact that you might need to do work based on whether or not the array has any values. The only solution I could find is to create a static helper method. So in my OO nature I created:

       1: function Helper() { }

       2: Helper.arraySize = function (associativeArray) {

       3:                                 var count = 0;

       4:                                 for (var i in associativeArray) {

       5:                                     count++;

       6:                                 }

       7:                                 return count;

       8:                             }

So now if I need to check the length of an “associative array” I can do so via:

       1: // Displays 2

       2: var size = Helper.arraySize(myArray);

       3: alert(size);

Might seem like a long way round but it is the only method I found thus far that facilitates my use case. Don’t forget to include the JS file if you have put it in a separate file Winking smile �