How to cancel a debounced function after it is called and before it executes?

Question

I create a debounced version of a function with underscore:

var debouncedThing = _.debounce(thing, 1000); 

Once debouncedThing is called...

debouncedThing(); 

...is there any way to cancel it, during the wait period before it actually executes?

Answer 1

If you use the last version of lodash you can simply do:

// create debounce const debouncedThing = _.debounce(thing, 1000);  // execute debounce, it will wait one second before executing thing debouncedThing();  // will cancel the execution of thing if executed before 1 second debouncedThing.cancel() 

Another solution is with a flag:

// create the flag let executeThing = true;  const thing = () => {    // use flag to allow execution cancelling    if (!executeThing) return false;    ... };  // create debounce const debouncedThing = _.debounce(thing, 1000);  // execute debounce, it will wait one second before executing thing debouncedThing();  // it will prevent to execute thing content executeThing = false; 

Answer 2

Old, but adding a note for anyone else who gets here.

The docs (I'm looking at 1.9.1 right now) say that you should be able to do:

var fn = () => { console.log('run'); }; var db = _.debounce(fn, 1000); db(); db.cancel(); 

This would do the thing that the OP wants to do (and what I wanted to do). It would not print the console message.

I have never been able to get this to work. I have looked high and low for a .cancel() as promised in the Underscore doc and I cannot find it.

If you are using Underscore, use the flag option in the accepted answer by Carlos Ruana. My requirements lamentably (in my opinion) do not allow an upgrade (in my opinion) from Underscore to Lodash. Underscore has less functionality but it is more functional than without.