Get Multiple Values in the select list using Javascript

function getMultipleSelectedValues(filed_name)
{
var selObj = document.getElementById(filed_name);
var selectedArray = new Array();
var countObj = selObj.options.length;
var arr_count = 0;
for(var i = 0 ; i < countObj ; i++)
if (selObj.options[i].selected) {
selectedArray[arr_count] = selObj.options[i].value;
arr_count++;
}
return selectedArray;
}