Question

I have a javascript function that runs every 3 seconds, is there any way to do nothing if a previous instance of the function is already running?

Answer 1

I assume you are running heavy function with setInterval and want to skip one tick if previous one has not completed.

Then, instead of

function yourfoo() {
   // code
}

setInterval(yourfoo, 3000);

do:

function yourfoo() {
   // code
   setTimeout(yourfoo, 3000);
}

setTimeout(yourfoo, 3000);

This guarantees next call is not scheduled until previous one is completed.