CODEWITHSUNDEEP
javascriptperformancesetinterval
Rafie
Rafie

Reputation: 589

Is it possible to have "setInterval" set too fast?

I have a setinterval function in my javascript that I want to be as fast as possible, i.e. check the status of an event every 1ms. Is it possible that this would be asking too much from a user's browser? It seems to work just fine, but I am wondering if its a bad practice.

Upvotes: 4

Views: 3311

Answers (6)

dmonaldo
dmonaldo

Reputation: 309

Ben Cherry has a good article about this where he tests different browsers to find how fast setInterval can be before it becomes unreliable. The speed at which a setInterval or setTimout fires is dependent on the browser.

In particular, if you’re looking for consistent timer intervals across browsers, you have to use something >15ms.

So if you can set the time greater than 15ms you won't run into problems.

Upvotes: 0

Louis Loudog Trottier
Louis Loudog Trottier

Reputation: 487

is an while loop too slow for you?

while (condition)
  {
  //code block to be executed
  }

i know i'm not ansering your question but, i think there is no better ways to do something like that...

Upvotes: 0

SeanCannon
SeanCannon

Reputation: 77986

It is not only possible, it's quite common. It's a race-condition by its very nature. If you depend on the code inside the callback to be executed before the next interval, use a recursive setTimeout instead.

Also, unless your interval is called lockUpBrowser, that duration between callbacks is likely much too short for realistic performance handling.

(function myRecursiveTask() {
    // Do your task here
    myTask();

    if (!someConditionToAllowABailOut) {
        setTimeout(myRecursiveTask, 100); // 100ms loop
    }
}());

Upvotes: 8

Mike Brant
Mike Brant

Reputation: 71384

I would certainly question the need for such an approach. What are you needing to check for every 1ms that you can't check for every 10ms, 100ms, or every second?

Are you 100% certain that the check functionality that you will run every will always execute in < 1ms such that you don't have multiple check processes stacking up to run.

How much memory and CPU does the process take, and are you going to potentially slow down the user's browser to the point where simply actions like scrolling become painful for the user?

Upvotes: 1

zzzzBov
zzzzBov

Reputation: 179086

Yes, if the function reference passed to setInterval takes longer to execute than the interval, calls to the function will queue and bog down the browser. If you're trying to perform an animation and want to change each step as fast as possible, there is a requestAnimationFrame function that should be used for modern browsers. Personally, I've never needed to perform a function faster than every 15ms.

Upvotes: 1

Jakub Konecki
Jakub Konecki

Reputation: 46008

setInterval is not guaranteed to execute at precisely the interval specified. It will execute as soon as possible, but since javasript is single-threaded and some other code may execute at this time your callback may be delayed.

If you're using setInterval with 1ms than you're probably trying to solve your problem in a wrong way.

Upvotes: 4

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