如何从JavaScript中的无限运行循环中退出？

Question

Is it possible to stop an infinite loop from running at all?

Right now I am doing something like this:

var run = true;

loop ({
  if(run) {
  whatever
  }
}, 30),

Then when I want to stop it I change run to false , and to true when I want to start it again.

But the loop is always running whatever I do. It just not executing the code inside.

Is there a way to stop it completely? and make it start again when I want?

Answer 1

If I am understanding your question correctly, what you need is the break keyword. Here 's an example.

Answer 2

SetInterval will give you a loop you can cancel.

setInterval ( "doSomething()", 5000 );

function doSomething ( )
{
  // (do something here)
}

Set the interval to a small value and use clearinterval to cancel it

Answer 3

function infiniteLoop() {
    run=true;
    while(run==true) {
        //Do stuff
        if(change_happened) {
            run=false;
        }
    }
}
infiniteLoop();

Answer 4

It may not be exactly what you are looking for, but you could try setInterval .

var intervalId = setInterval(myFunc, 0);

function myFun() {
    if(condition) {
        clearInverval(intervalId);
    }
    ...
}

setInterval will also not block the page. You clear the interval as shown with clearInterval .

Answer 5

Use a while loop

while(run){
    //loop guts
}

When run is false the loop exits. Put it in a function and call it when you want to begin the loop again.

Answer 6

The problem is that javascript only has a single thread to run on. This means that while you are infinitely looping nothing else can happen. As a result, it's impossible for your variable to ever change.

One solution to this is to use setTimeout to loop with a very small time passed to it. For example:

function doStuff(){
   if(someFlag){
      // do something
   }

   setTimeout(doStuff,1);
}

doStuff();

This will give the possibility for other actions to make use of the thread and potentially change the flag.