Javascript setInterval function to clear itself?

问题:

myInterval = setInterval(function(){
     MyFunction();
},50);

function MyFunction()
{
    //Can I call clearInterval(myInterval); in here?
}

The interval's not stopping (not being cleared), if what I've coded above is fine then it'll help me look elsewhere for what's causing the problem. Thanks.

EDIT: Let's assume it completes a few intervals before clearInterval is called which removes the need for setTimeout.

回答1:

As long as you have scope to the saved interval variable, you can cancel it from anywhere.

In an "child" scope:

var myInterval = setInterval(function(){
     clearInterval(myInterval);
},50);

In a "sibling" scope:

var myInterval = setInterval(function(){
     foo();
},50);

var foo = function () {
    clearInterval(myInterval);
};

You could even pass the interval if it would go out of scope:

var someScope = function () {
    var myInterval = setInterval(function(){
        foo(myInterval);
    },50);
};

var foo = function (myInterval) {
    clearInterval(myInterval);
};

回答2:

clearInterval(myInterval);

will do the trick to cancel the Interval whenever you need it. If you want to immediately cancel after the first call, you should take setTimeout instead. And sure you can call it in the Interval function itself.

var myInterval = setInterval(function() {
  if (/* condition here */){
        clearInterval(myInterval);
   } 
}, 50);

see an EXAMPLE here.

回答3:

var interval = setInterval(function() {
  if (condition) clearInterval(interval); // here interval is undefined, but when we call this function it will be defined in this context
}, 50);

Or

var callback = function() { if (condition) clearInterval(interval); }; // here interval is undefined, but when we call this function it will be defined in this context
var interval = setInterval(callback, 50);

回答4:

From your code what seems you want to do is to run a function and run it again and again until some job is done...

That is actually a task for the setTimeout(), the approach is similar:

    var myFunction = function(){
      if( stopCondition ) doSomeStuff(); //(do some stuff and don't run it again)
        else setTimeout( myFunction, 50 );
    }
    myFunction(); //immediate first run 

Simple as that :)

Of course if you REALLY want to use setInterval for some reason, @jbabey's answer seems to be the best one :)

回答5:

You can do it by using a trick with window.setTimeout

var Interval = function () {
    if (condition) {
        //do Stuff
    }
    else {
        window.setTimeout(Interval, 20);
    };
};
window.setTimeout(Interval, 20);