javascript array.sort with undefined values

Question

How does Array.prototype.sort handle undefined values in an array?

var array = [1,undefined,2,undefined,3,undefined,4];
var array2 = [];
array2[         


        

Answer 1

It appears that the undefined values will fall to the bottom of the list. Here's some sample code to show you what happens:

var a = [1,undefined,2,undefined,3,undefined,4];
  a = a.sort();
  for( i = 0 ; i < a.length ; i++ )
  {
    alert( a[i] );
  }

This is, of course, the default behavior of JavaScript. If you overwrite the default behavior then only you will know.