Javascript doesn't have an "in" operator, so you can use this in_array function instead.

js-in_array.js

function in_array(val, arr, sep){
    /* Takes an array, joins it using sep (default = '|'), then 
    *  uses indexOf to test if val is in arr. Returns true or false.
    */

    if(!sep){
        var sep = "|";
    }

    var join = ["", arr.join(sep), ""].join(sep);
    var retc = join.indexOf(val);
    return retc != -1;

}