setInterval() behaviour with 0 milliseconds in JavaScript

javascript setinterval
João Gomes picture João Gomes · Oct 4, 2011 · Viewed 19k times · Source

In my application I found some JavaScript code that is using setInterval with 0 milliseconds, like so:

self.setInterval("myFunction()",0);

Obviously, this does not seem like a good idea to me. Can anyone tell me what will be the behaviour of setInterval here? ("myFunction" makes an AJAX call to the server)

I am asking this because I am having an irregular behaviour in my application. 90% of the times, the application behaves correctly and exactly one call to the server is made. However sometimes, multiple calls are made to the server (until now, maximum is 48 calls) and I am almost certain it is the fault of this line of code.

Answer

deadalnix picture deadalnix · Oct 4, 2011

Browser set a minimal value for the interval. Usualy 10ms, but it can depend on the browser. This means repeat this as fast as I'm possibly allowed. The W3C spec say 4ms : http://www.whatwg.org/specs/web-apps/current-work/multipage/timers.html#timers

This is correct but probably reveal a design error.

EDIT: By the way, it is bad practice to pass a string to setTimeout/setInterval, pass a function instead as javascript has first class functions.

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