Question

I’m wondering if it is possible in Javascript to call a function up to a number of N times to get a truthy value back. It should immediately return if the return is true. It should at least return regardless of the return value after N times.

I read a bit through existing resources and came to the point that it is not possible, but normally done with a callback function. Are there any patterns / best practices / examples for that?

Answer 1

I came up with the following implementation:

multitry = function(time, tries, func, callback) {
    counter = 0;
    timer = setInterval(function() {
        ((success = func(++counter)) || (counter >= tries))
            && !clearInterval(timer) 
            && callback(success, counter)      
        ;
    }, time);
};

For example to try 30 times each 250 milliseconds if the tag-editing has been enabled, you can run the following:

javascript:(function(){
    multitry = function(time, tries, func, callback) {
        counter  = 0;
        timer    = setInterval(function() {
            counter++;
            var value = func(counter);
            if (value || counter >= tries) {
                clearInterval(timer);
                callback(value, counter);
            }
        }, time);
    };
    multitry(
        250, 
        30, 
        function() {
            return $('#tagnames').length;
        }, 
        function (success) {
            console.log('Tag editor did open:', success);
        }
    );
}());