Poll until a condition is met

when_condition_met.js

function when_condition_met(fn_condition, fn_callback, interval, opt_max_attempt) {
    var poll_id;
    var run_count = 0;

    poll_id = setInterval(function () {
        if (typeof opt_max_attempt == "number" && run_count == opt_max_attempt) {
            clearInterval(poll_id);
            return; // possible run onfail callback.. If so refactor to be onject based params.
        }

        if (fn_condition()) {
            clearInterval(poll_id);
            fn_callback();
        }

        run_count++;
    }, interval);
}

/*  =========== USAGE  ===========
var notnull = null;
setTimeout(function(){
  notnull = {
    label: 'Some Value',
    value: 54
  };
}, 3500);

var _condition = function () {
console.log('testing...');
    return notnull !== null;
};
var _callback = function(){
	alert('Condition was met');
};
var _interval = 500;

when_condition_met(_condition, _callback, _interval, 4);
*/