Stmixing string with array variable to assign an id for an element in javascript

Stmixing string with array variable to assign an id for an element in
javascript

I´m trying to mix a string to assign variable(array) I don´t know what´s
wrong I can not get it work.
in php I will send array of id to javascript via json_encode(); I will get
like :arr= 100, 101, 102 etc.
Then in javascript with a conditon like this:
function xx (key, arr)
for (var v in arr){ //LOOP
var k = arr[v];
if (document.getElementById("swas"+k) != key) {
document.getElementById("swas"+k).className =" colorme";
}
}
What have I done wrong ?