Question

I have a sparse array in Jscript, with non-null elements occuring at both negative and positive indices. When I try to use a for in loop, it doesn’t traverse the array from the lowest (negative) index to the highest positive index. Instead it returns the array in the order that I added the elements. Enumeration doesn’t work either. Is there any method that will allow me to do that?

Example

arrName = new Array(); arrName[-10] = 'A'; arrName[20] = 'B'; arrName[10] = 'C'; 

When looping through, it should give me A then C the B.

Answer 1

Technically, ‘A’ isn’t in the Array at all since you can’t have a negative index. It is just a member of the arrName object. If you check the arrName.length you will see that it is 21 (0,1,2,…,20) Why don’t you use a plain object instead (as a hashtable). Something like this should work:

<script type='text/javascript'> //define and initialize your object/hastable var obj = {}; obj[20] = 'C'; obj[10] = 'B'; obj[-10] = 'A';  // get the indexes and sort them var indexes = []; for(var i in obj){     indexes.push(i); } indexes.sort(function(a,b){     return a-b; });  // write the values to the page in index order (increasing) for(var i=0,l=indexes.length; i<l; i++){     document.write(obj[indexes[i]] + ' '); } // Should print out as 'A B C' to the page </script>