You are invoking the function instead of binding a function reference as handler to it, and remember quotes around the selector.
$(#selectRating).bind("focus", disableOption(0)); //This just invokes the function as you try to bind the handler.
should be
$("#selectRating").bind("focus", function(){
disableOption(0);
});
and you just need to do:
$("#selectRating").children(":eq(" + pos + ")").prop("disabled", true);
Or simplify it to:
function disableOption(pos) {
$(this).children(":eq(" + pos + ")").prop("disabled", true);
}
function addEventListeners() {
$('#selectRating').bind("focus", function(){
disableOption.call(this, 0);
});
}