Call setTimeout without delay

Question

Quite often see in JavaScript libraries code like this:

setTimeout(function() {
    ...
}, 0);

I would like to know why use such a wrapper

Answer 1

Apart from previous answers I'd like to add another useful scenario I can think of: to "escape" from a try-catch block. A setTimeout-delay from within a try-catch block will be executed outside the block and any exception will propagate in the global scope instead.

Perhaps best example scenario: In today's JavaScript, with the more common use of so called Deferreds/Promises for asynchronous callbacks you are (often) actually running inside a try-catch. Deferreds/Promises wrap the callback in a try-catch to be able to detect and propagate an exception as an error in the async-chain. This is all good for functions that need to be in the chain, but sooner or later you're "done" (i.e fetched all your ajax) and want to run plain non-async code where you Don't want exceptions to be "hidden" anymore. AFAIK Dojo, Kris Kowal's Q, MochiKit and Google Closure lib use try-catch wrapping (Not jQuery though).

(On couple of odd occasions I've also used the technique to restart singleton-style code without causing recursion. I.e doing a teardown-restart in same loop).