Proposal: Conditional `catch` in Promises

Isiah Meadows isiahmeadows at
Wed Apr 25 15:31:17 UTC 2018

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> 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.
> _______________________________________________
> es-discuss mailing list
> es-discuss at
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the es-discuss mailing list