Test: http://w3c-test.org/url/urlsearchparams-constructor.html, landed at https://github.com/w3c/web-platform-tests/pull/4523. Standard: https://github.com/whatwg/url/issues/27, landed at https://github.com/whatwg/url/pull/175.

record<> is not supported yet.

Comment on attachment 8827079 [details] [diff] [review] url.patch > >-/* static */ already_AddRefed<URLSearchParams> >-URLSearchParams::Constructor(const GlobalObject& aGlobal, >- URLSearchParams& aInit, >- ErrorResult& aRv) >-{ >- RefPtr<URLSearchParams> sp = >- new URLSearchParams(aGlobal.GetAsSupports(), aInit); >- >- return sp.forget(); >-} Why removing this is ok? Why do we have this non-standard ctor? Was it at some point in the spec? Blink at least seems to allow URLSearchParams as a param to ctor, so it is very much not clear to me why this change is ok.

Or is removing that ok since URLSearchParams has stringifier?

It's okay because URLSearchParams has iterable<>. The only observable difference is a custom iterator and I added a test for that.

Comment on attachment 8827079 [details] [diff] [review] url.patch Ok, thanks Anne. couldn't you in the test check that the right exception is thrown.

It would be better if we added those tests to web-platform-tests.

Comment on attachment 8827371 [details] [diff] [review] test for WPT This patch has been sent as PR on github.

Pushed by amarchesini@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/293533db8cc7 Construct URLSearchParams from sequence or from string, r=smaug

Do you mind sending an intent to ship for this?

I've had a go at updating the docs on this feature: https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams/URLSearchParams https://developer.mozilla.org/en-US/Firefox/Releases/53#DOM_HTML_DOM And what I have there at the moment seems to work fine. However, I'm a little confused - the most up to date WebIDL says this: [Constructor(optional (sequence<sequence<USVString>> or record<USVString, USVString> or USVString) init = ""), Now, I might be wrong, but the way I understand it a sequence is basically an array of objects. And I'm not sure what a record is... I've tried experimenting with this: 1. when I try to pass an array of parameter USVStrings into URLSearchParams(), it throws a typeerror in Fx and Chrome 2. when I try to pass an object containing parameter USVStrings into URLSearchParams(), it works, but then any call to the object instance (e.g. paramObj.get('foo')) just returns null, even if I know the param is present in one of the USVStrings. Can you give me some quick examples of using a sequence or record in this context? Feel free to hit me up over mail/IRC to avoid polluting the bug too much.

Nested sequence of strings (note that the inner array has to be two items exactly): new URLSearchParams([["a", "1"], ["b", "2"]]). Record: new URLSearchParams({a: "1", b: "2"}). Thanks for documenting!

And the record (object) support has been added to Firefox 54 in Bug 1331580, not Firefox 53 in this bug.

Cool, thanks both; I get it now. I've updated the ctor page to mention the sequence, but I still don't see the record syntax working in the latest nightly. Too new? I any case, I'll leave it for now, and fix it up when I come to write the Fx54 release notes.

It works fine here, 55.0a1 (2017-03-06) (64-bit).