Nothing happens after Prompt

I am trying to set up an if/else if statement within a loop that is started by a prompt. As I have it now, nothing happens after inputting a number into the prompt and hitting OK. I am just starting out so please be gentle. Thanks!

    $(function() {

    var number = parseInt(prompt("Let me see a number:"));

    for(var i = 0; i <= number; i++) {
     if ( digit %15 == 0) {
            return "Ping-Pong";
        }
        else if (digit %5 == 0) {
            return "Pong";
        }
        else if (digit %3 == 0) {
            return "Ping";
        }
        else {
            return i;
        }
};

});