Does Javascript have support for multithreading?

Question

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Why doesn't JavaScript support multithreading?

Is there some way to spawn new threads for running tasks (for network stuff or some heavy calculations) to work in parallel?

http://stackoverflow.com/questions/39879/why-doesnt-javascript-support-multithreading?rq=1 — prusswan, Sep 07 '12 at 21:19
Keep in mind that *multi-threading* is a specific kind of *concurrency*. — , Sep 07 '12 at 21:25

score 6 · Accepted Answer · answered Sep 07 '12 at 21:23

Yes and no.

You can use Web Workers to create background threads, but it's far from all browsers that support that. Internet Explorer for example doesn't have support for it until version 10.

In regular Javascript code there is no multi threading. Javascript is a strictly single threaded language.

score 3 · Answer 2 · answered Sep 07 '12 at 21:20

3

Yes, via web workers. See documentation: https://developer.mozilla.org/en-US/docs/DOM/Using_web_workers?redirectlocale=en-US&redirectslug=Using_web_workers

answered Sep 07 '12 at 21:20

Esailija

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score 3 · Answer 3 · answered Sep 07 '12 at 21:21

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You can, but only in modern browsers that support Webworkers

http://www.html5rocks.com/en/tutorials/workers/basics/

answered Sep 07 '12 at 21:21

Clyde Lobo

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score 1 · Answer 4 · answered Sep 07 '12 at 21:22

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JS does not directly support multithreading but I believe you could emulate it by using several IFRAMES running a same script or different scripts. I'm just speculating.

answered Sep 07 '12 at 21:22

Claudi

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Iframes run in the same thread as the top window. – Esailija Sep 07 '12 at 21:25
Really? Is it true for all browsers? I thought IFRAMES were run in different threads :S – Claudi Sep 07 '12 at 21:32
Very easy to test since jsfiddle code runs in a different iframe, if you make a `while(true){}` loop your whole tab/window will freeze. – Esailija Sep 07 '12 at 21:34

Does Javascript have support for multithreading?

4 Answers4