Just one thought: > Of course, in the top-level invocation it might be a good idea to use a `catch`
after years of engine developers advocating "avoid try/catch as much as possible because it de-opts and slow down code and JIT and you name it", above suggestion doesn't really look like an "of course". Using a proper `.catch()` within the async returned promise is probably the best approach. Best Regards On Fri, Oct 14, 2016 at 4:25 PM, Alan Johnson <[email protected]> wrote: > To perhaps clarify this point a bit, it is *very important* to `.catch()` > and react appropriately at the ends of promise chains. If synchronous code > fails for an unexpected reason, a visible crash will definitely happen. > This is not the case for promises, because there’s no way for the runtime > to know whether that promise is just some middle step in the chain, in > which case you’d want to propagate rejection, rather than throw a > synchronous exception. Having unexpected errors be silently swallowed is > definitely a problematic property of promises, which you have to guard > against. > > It probably would be possible for the runtime to report crashes of > promises that have no registered `.then()`. The only problem is, it’s > totally possible the programmer is going to attach a `.then()` or > `.catch()` later on to a promise that has already failed. Some promise > libraries offer a `.done()` that has the semantics of “crash if this > promise rejects”. But arguably, this should be the normal behavior, with an > opt-out instead, so that it is assumed that you want rejected promises > without any `.then()`s to throw synchronous exceptions. Something like a > `.noFail()` could opt out > > On Oct 14, 2016, at 09:30, Bergi <[email protected]> wrote: > > Jordan Rome schrieb: > > My apologies if this has already been discussed but what is the "preferred" > pattern for using await ? Since await, which runs on promises, will now > throw if the promise is rejected (preventing execution of code after the > await and killing the process in Node), is it neccesary to always be > wrapping await in try/catch? > > > No. Just like in synchronous code, you only wrap a part of your code in > try-catch if you actually want to *handle* an exception. > > If you don't handle it, it will bubble as usual and reject the promise > returned by the `async function`. Let the caller deal with the exceptions > you can't handle - just like always. > Of course, in the top-level invocation it might be a good idea to use a > `catch` (or the `.catch()` method) to catch any exceptions and log them to > whereever you want if you don't want to get an unhandled rejection, but > those are usually exceptions you *don't expect* so you might not need to > deal with them at all. > > - Bergi > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
