[End User]

I have a form that lets people copy items from one select list to another, but I want to prevent them from putting duplicate items into the second list. In other words, they can pick as many items from the first list as they want, but they can't pick and add the same one twice.

In the code below, what would be the best way to prevent adding duplicate items to the "destList.options" array?

HTML Code:

// Populate  destination with  items from new array
for ( var j = 0; j < newDestList.length; j++ ){

    if ( newDestList[ j ] != null ){

	      destList.options[ j ] = newDestList[ j ];

    }

}