如何循环 setTimeout() 以及如何停止循环

Question

I have a setTimeout() looped which works just fine except that I don't know how to stop when I need it stop it.

I have read a few posts with similar inquiries but for some reason I cannot make those solutions fit my case and here's hoping someone can help me out.

var timeout_function;
function testFunction(param1, param2, param3, action){
    timeout_function = setTimeout(function start() {
        if(action == 'start'){
            primaryTestFunction(param1, param2, param3);
            setTimeout(start, 10000);
        }else{
            clearTimeout(timeout_function);
        }
    }, 10000);
}

Alright, so the idea is that when I run testFunction() and it includes the action "start" the setTimeout() loop will begin and when I run testFunction() again but with action "stop" or anything else for that matter, it should break the loop by running clearTimeout() but that's not the case.

I even placed another clearTimeout() outside timeout_function and within an if() statement to catch the stop action and run clearTimeout() but it doesn't work.

I can start it and the loop runs accordingly but I cannot make it stop. Thanks in advance,

Answer 1

First, in case this is causing confusion, setTimeout does not return a function, but a integer id. When you pass that id to clearTimeout it will not execute callback function passed to setTimeout . But clearTimeout will only clear the function associated with the id passed to it, not any other timers that may be concurrently active.

So, on line 6, when you call setTimeout again, you aren't saving the id it returns anywhere, and therefore you have no way of clearing it, so it will execute regardless if you clear the setTimeout function on line 3.

Now for the question: it may be possible to what you are trying to do with timeouts, but I think it would be much easier to use the similar function setInterval . It works the exact same way as timeout, but it executes the function passed to it on indefinitely on an interval until it is cleared.

This way you could just

const intervalID = setInterval (() => {
                    primaryTestFunction(param1, param2, param3);
                   }, 10000);
                  

And then clearInterval(intervalID) when you want to stop it.

Answer 2

 var loop1 = setInterval(()=> { if(action == 'start'){ primaryTestFunction(param1, param2, param3); setTimeout(start, 10000); } else{ clearInterval(loop1); } },100);