Javascript semaphore / test-and-set / lock?

Question

Is there such a thing as an atomic test-and-set, semaphore, or lock in Javascript?

I have javascript invoking async background processes via a custom protocol (the b

Answer 1

I had the same issue, here is how I solved it. It works fine for two concurrent processes. If you have three processes or more, it is possible that two processes start together.

var isRunning = false;
...
var id = setInterval(function(){ //loop until isRunning becomes false
            if (!isRunning){
                isRunning = true;
                //do something synchronous or use a promise
                isRunning = false;
                clearInterval(id); // stop the loop here
            }
        , 10);

It is better than the while loop because it solves concurrency/async issues for reading/setting isRunning.