[whatwg] Proposal: Add window.getLastError (or modify invocation arguments of window.onerror)

Oliver Hunt oliver at apple.com
Mon Feb 4 14:44:37 PST 2013

On Feb 4, 2013, at 2:40 PM, Garrett Smith <dhtmlkitchen at gmail.com> wrote:
>>> That's fair enough. Though not all exceptions are Errors -- DOMException
>>> currently isn't, though I think some people want it to somehow inherit
>>> from
>>> Error.
> Why not?

That's something lost in the mists of time, however just asking it w.r.t DOMException misses the point that any value in js can be thrown - there's no requirement that it be an object, let alone a subtype of Error.

>>> For example, some devs may be interested in the "Error" object's
>>>> "name" property, which is already a part of the object today but is not
>>>> provided to "window.onerror" callbacks.  And again, if additional
>>>> properties are added in the future, it's just more and more properties
>>>> that
>>>> may need to get incrementally added to the "window.onerror" invocation
>>>> arguments list.  For example, I proposed the addition of an "innerError"
>>>> property (or some would call it "cause") for chaining errors and masking
>>>> internal errors that consumers shouldn't see, instead providing a
>>>> customer-facing message.
>>> Yeah.
> Yep. Pass an error object with a stack trace.

That's tricky - what is your "stack trace"?  You can very easily end up leaking private information across frames.


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