Manipulating Arrays in JavaScript

In my recent work I have had to do a lot of array manipulation in JavaScript. While doing this I learned a few tricks, that I did not want to forget and thought others might benefit from.

Some of these things are simple, but I include here for completeness. I welcome any feedback on any array tricks that you have learned.

1. Adding to an array
   

   var array = [];
   array.push(5835);

   
   
   
   


2. Deleting from an array
   

   var array =[];
   array.push(5835); // index of 0
   array.push(6835); // index of 1
   array.push(7835); // index of 2
   delete array[1];

   
   The resulting array would be [5835, 7835], but the indexes would still be [0,2]. JavaScript does not reorder the indexes to always be zero based.
   
   
   


3. Array Looping
   
   Although you can loop through an array normally:
   

   
   for(var i = 0; i < array.length; i++) {
     alert("Index was " + i + ", value was " + array[i]);
   } 

   
   You can get into trouble, if you are doing array manipulation like deleting. Like I stated in #2, there is no more index 1, so you would get a JavaScript error.
   Because of this I have become a fan of the following loop:
   

   
   for(var i in array) {
     if (typeof array[i] == "function") {
       continue;
     }
     alert("Index was " + i + ", value was " + array[i]);
   }

   
   A couple of things to note, first is the check to make sure the element is not a function. All arrays have a remove method inherent in them, so you need to skip that. Second, you will see that the indexes are indeed, 0, 2 and not 0, 1, if you use the dataset from #2.
   
   
   

More to come later...