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paulmillr / es6-shim

ECMAScript 6 compatibility shims for legacy JS engines
http://paulmillr.com
MIT License
3.11k stars 387 forks source link

Leaky abstraction in the use of window.postMessage()? #410

Open istarnx opened 8 years ago

istarnx commented 8 years ago

Hi guys,

It looks like you're using window.postMessage("zero-timeout-message", ...) to implement an internal enqueue method. This bit me while running unit tests in PhantomJS. We have a message event listener registered on the window, and it's getting invoked with "zero-timeout-message", which causes it to break unless we explicitly filter your message type.

Does it make sense for your clients to have to guard against your message types? I'm not sure of convention in this case, but it smells odd, so I wanted to bring it to your attention.

Thank you!

ljharb commented 8 years ago

This is a fair concern. However, a postMessage handler should always be only reacting to explicit message types, never broadly reacting to every event - so I'm not sure it's a real issue.

I'll leave this open in case others have thoughts.

ljharb commented 8 years ago

One possibility is overriding addEventListener to filter out our postMessage events, but that seems like it'd introduce a lot of latency for users for minimal gain :-/