Array.prototype.contains

gistfile1.txt

Array.prototype.contains = function(k, callback) {
	var self = this;
    return (function check(i) {
        if (i >= self.length) {
            return callback(false);
        }

        if (self[i].id === k.id) {
            return callback(true);
        }

        return process.nextTick(check.bind(null, i+1));
    }(0));
}

you could also use setTimeout