setTimeout() about scala-js-dom HOT 5 CLOSED

I concur, all the mess I made lately around async testing was due to the fact that I was passing a block instead of function into the setTimeout method.. It made me think that PhantomJS executes setTimeout immediately whereas it was due to this thing :-)

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PR welcome.
Note that

def setTimeout(handler: () => Unit, timeout: Int): Int = ???

is incorrect, it must be a js.Function0. Besides, Unit return types in callbacks should typically be Any instead, so it should be:

def setTimeout(handler: js.Function0[Any], timeout: Int): Int = ???

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Besides, Unit return types in callbacks should typically be Any instead

@sjrd I have a question about this. I always thought it to be better, if we could specify the API author's intent more clearly. So, when a function argument is not expected to return a meaningful value, I've preferred to use () => Unit, rather than js.Function0[Any].

Should I change such APIs to allow return Any as you recommended? And I'd like to know if there is specific reason behind it.

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In general, of course, we should be as precise as possible. But in the case of a callback returning Unit, it means more that you don't care what the result will be because you're not going to use it. I would agree with conveying the api's intent, in general. But for this user case, specifying Any helps the type inference to do the right thing. Scala APIs do the same: look at definitions of foreach: they take functions returning a generic type U (which, in contravariant position, is basically the same as Any) instead of Unit.

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Thanks for the explanation. I suppose I better change my sources to confirm to this, if Scala API defines the signature of foreach in such a way.

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