Image element src property does not allow URL assignment #43066
Description
Bug Report
🔎 Search Terms
image src dom
🕗 Version & Regression Information
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about 4.3.0
⏯ Playground Link
Playground link with relevant code
💻 Code
let image = document.createElement('img');
image.src = new URL("http://google.com");
console.log(image.src)🙁 Actual behavior
Type 'URL' is not assignable to type 'string'.(2322)
🙂 Expected behavior
Compiles cleanly (confirmed supported per whatwg/html#6440)
Activity
TimvdLippe commentedon Mar 3, 2021
Previous occurrences of this kind of issue:
At this point, should we assume that
USVStringimpliesstring | URL? The handling ofUSVStringis currently implemented in https://github.com/microsoft/TypeScript-DOM-lib-generator/blob/07ea4e8bf58f9907d22024cca6433e002fffd251/src/helpers.ts#L6 I am not sure how many other IDL definitions useUSVString, but wouldn't accept aURL(which would be implicitly.toString'd per the linked HTML issue)CC Domenic Denicola (@domenic) do you mind confirming if we can assume
type USVString = string | URLin TypeScript or am I still misunderstanding the terminology here 😄domenic commentedon Mar 3, 2021
It's more subtle than that. Every DOMString or USVString will convert any input to a string. Technically, everything in JavaScript is convertible to a string, at the very least through Object.prototype.toString(). So hard-coding URL doesn't make sense to me.
TimvdLippe commentedon Mar 3, 2021
Ah right. Yes I understand that now. Thanks again for the explanation!
DanielRosenwasser commentedon Mar 4, 2021
You want separate types for reading and writing properties, which Ryan Cavanaugh (@RyanCavanaugh) is iterating on over at #42425.
I guess we did discuss a few things in a previous design meeting about how much of
lib.d.tsneeded to change and punted on it, but this seems like a reasonable one (write ofURL | string, read ofstring).DanielRosenwasser commentedon Mar 4, 2021
We'd want to be more permissive to a degree; letting anything in with a
toString()seems undesirable, whereas unblocking a scenario like assigningURLinstances toa property calledtheurlsrcproperty seems reasonable.RyanCavanaugh commentedon Mar 9, 2021
Tracking at #2521. We can update the lib once that's checked in