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);
         


        

Answer 1

Well you can do

var interval = setInterval(function() {}, 1000);
interval = clearInterval(interval);
if (typeof interval === 'undefined'){
...
}

but what are you actually trying to do? clearInterval function is an always success function and it will always return undefined even if you call it with a NaN value, no error checking in there.