Is there a way to check if a var is using setInterval()?

Question

For instance, I am setting an interval like

timer = setInterval(fncName, 1000); 

and if i go and do

clearInterval(timer); 

it does clear the interval but is there a way to check that it cleared the interval? I've tried getting the value of it while it has an interval and when it doesn't but they both just seem to be numbers.

Answer 1

There is no direct way to do what you are looking for. Instead, you could set timer to false every time you call clearInterval:

// Start timer var timer = setInterval(fncName, 1000);  // End timer clearInterval(timer); timer = false; 

Now, timer will either be false or have a value at a given time, so you can simply check with

if (timer)     ... 

If you want to encapsulate this in a class:

function Interval(fn, time) {     var timer = false;     this.start = function () {         if (!this.isRunning())             timer = setInterval(fn, time);     };     this.stop = function () {         clearInterval(timer);         timer = false;     };     this.isRunning = function () {         return timer !== false;     }; }  var i = new Interval(fncName, 1000); i.start();  if (i.isRunning())     // ...  i.stop(); 

Answer 2

The return values from setTimeout and setInterval are completely opaque values. You can't derive any meaning from them; the only use for them is to pass back to clearTimeout and clearInterval.

There is no function to test whether a value corresponds to an active timeout/interval, sorry! If you wanted a timer whose status you could check, you'd have to create your own wrapper functions that remembered what the set/clear state was.