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Blob constructor error message when passing a string is misleading #38856
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Oh looks like this is intentionally not supported
Line 106 in 7919ced
Can we add a reason why to the docs?
Here's my interpretation of why a string is not accepted: The specs dictates that the param must be a
sequence<BlobPart>. It's not clear to me if the string is interpreted as aUSVString(which doesn't seem to be a sequence in that specification), or aDOMString(which is defined as asequence<unsigned short>andunsigned shortis not aBlobPart), but either waynew Blob('string')is meant to fail.Now I agree the error message is misleading, for reference here's the error messages thrown by some browsers:
- Chromium:
TypeError: Failed to construct 'Blob': The provided value cannot be converted to a sequence. - Firefox:
TypeError: Blob constructor: Argument 1 can't be converted to a sequence. - Safari:
TypeError: Value is not a sequence
Reacted by bl-ue, Ethan Arrowood and Anna Henningsen- Chromium:
This works just fine, however:
new Blob(['hello'])Reacted by Ethan Arrowood@Ethan-Arrowood ... just as a heads up since you're using
Blob... sometime in the next two months as time allows, I will be working onBlobsupporting async data sources. It won't impact the API usage at all, but figured it's worthwhile to give a heads up.Yes I saw that, very excited for it. I'm using this in undici-fetch and it'll be a nice perf boost if blob can support the async iterator sources directly 😄
- changed the title
[-]Support string as source for Blob[/-][+]Blob constructor error message when passing a string is misleading[/+]on Jun 1, 2021 - added a commit that references this issue
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on Oct 10, 2022
Is your feature request related to a problem? Please describe.
Working with the new Blob api. Cannot instantiate using a string though I don't see why not.
Describe the solution you'd like
Maybe I'm misunderstanding, but I think strings to implement [Symbol.iterator]; does that not make it an instance of Iterable?
Describe alternatives you've considered
Plenty of work arounds - think this would make for a good addition.
Happy to contribute this feature too