Proposal: Conditional `catch` in Promises

[Bob Myers]

What do you mean by "approach TypeScript"? Do you mean propose this feature
to the TS team? TS is not about new language features (with a few
exceptions). It's about typing. They're quite careful about not forking the
language.

>  Not sure if that supports typed errors

No, it doesn't.

Bob

On Wed, Apr 25, 2018 at 9:49 PM, Michael J. Ryan <tracker1 at gmail.com> wrote:

> Maybe approach typescript on this one... Not sure if that supports typed
> errors like C# does, but would probably suit you well.
>
> On Wed, Apr 25, 2018, 08:31 Isiah Meadows <isiahmeadows at gmail.com> wrote:
>
>> I'd still prefer we wait until pattern matching [1] gets addressed first,
>> then tackling this. Error types are represented about 50 different ways in
>> JS, with subtyping only being one (used by the standard kind of). Node
>> appends an `err.code`, and the DOM adds a similar type, just using a common
>> error subclass. And in some cases where errors are planned (but exceptions
>> are more convenient), you sometimes see non-errors thrown. So there needs
>> to be a means of catching all of them, and `if` checks get verbose and
>> noisy in a hurry.
>>
>> On Wed, Apr 25, 2018, 00:11 Ayush Gupta <ayushg3112 at gmail.com> wrote:
>>
>>> We could potentially provide the same functionality in `try/catch` by
>>> extending the signature of `catch` to
>>>
>>> ```js
>>> try {
>>>
>>> } catch(<expression_var>, <function_expression>) {
>>>
>>> }
>>> ```
>>>
>>> If `<function_expression>` evaluates to truthy, invoke the `catch`
>>> block, otherwise don't.
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>>> es-discuss at mozilla.org
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>>>
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>
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