setTimeout(0) vs window.postMessage vs MessagePort.postMessage

Question

Apparently, using window.postMessage is a preferred way to queue an async javascript callback over window.setTimeout(fn, 0) across all modern browsers. I could

Answer 1

[UPDATE] Added a test for setImmediate and a JSFiddle. Related, there's a cross-browser implementation of setImmediate and ASAP library used by Q for a promise resolution/rejection.

I went ahead and did some timing, using a modified version of David Baron's code, the results are below:

setTimeoutMC - using MessageChannel
setTimeoutPM - using window.postMessage
setTimeout(0) - using setTimer

IE10:

2000 iterations of setTimeoutMC took 126 milliseconds.
2000 iterations of setTimeoutPM took 190 milliseconds.
2000 iterations of setTimeout(0) took 7986 milliseconds.

Chrome v29.0.1547.66:

2000 iterations of setTimeoutMC took 144 milliseconds.
2000 iterations of setTimeoutPM took 81 milliseconds.
2000 iterations of setTimeout(0) took 10589 milliseconds.

Clearly, window.postMessage is the winner here (considering the level of existing cross-browser support for it). The looser is window.setTimeout(fn, 0) and should be avoided wherever possible.

Code: