Delay function from running for n seconds then run it once. (2minute question)

Question

TLDR I have a function that runs on the end of a pan in an openlayers map. Don't want it to fire continously.

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I have a function that runs on the end of panning a map. I want it so that it will not fire the function until say 3 secconds after the pan has finished. Although I don't want to queue up the function to fire 10 or so times like setTimeout is currently doing.

How can I delay a function from running for n seconds then run it only once no matter how many times it has been called?

    map.events.register("moveend", map, function() {
      setTimeout(SetLocation, 5000);
    });

Moveend:

moveend - triggered after a drag, pan, or zoom completes

The code above even using setTimeout(func, delay); still fires multiple times when it runs. How can I prevent this?

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Answer 1

Well, meeting your requirements, you could build a simple function wrapper:

var executeOnce = (function (fn, delay) {
  var executed = false;
  return function (/* args */) {
    var args = arguments;
    if (!executed) {
      setTimeout(function () {
        fn.apply(null, args); // preserve arguments
      }, delay);
      executed = true;
    }
  };
});

Usage examples:

With your code:

map.events.register("moveend", map, executeOnce(SetLocation, 5000));

Other usages:

var wrappedFn = executeOnce(function (a, b) {
  alert(a + ' ' + b);
}, 3000);

wrappedFn('hello', 'world');
wrappedFn('foo', 'bar'); // this won't be executed...

The wrapped function will be delayed the specified amount of time and executed only once.