This is the general structure of my code:
(async () => {
try {
const asyncActions = []
for (let i = 0; i < 3; i++) {
await new Promise((resolve, reject) => setTimeout(resolve, 1000))
for (let j = 0; j < 3; j++) {
asyncActions.push(new Promise((resolve, reject) => setTimeout(reject, 1000)))
}
}
await Promise.all(asyncActions)
console.log('all resolved')
}
catch (e) {
console.log('caught error', e)
}
})()
I expect this to catch any rejections happening in asyncActions
because they should be handled by Promise.all()
, but somehow they are unhandled? The console shows the following:
(node:9460) UnhandledPromiseRejectionWarning: undefined
(Use `node --trace-warnings ...` to show where the warning was created)
(node:9460) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:9460) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
(node:9460) UnhandledPromiseRejectionWarning: undefined
(node:9460) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
...
(node:9460) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)
(node:9460) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 2)
...
Why are they not handled by Promise.all()
and then caught in the catch block?
I also noticed that when I replace both the new Promise(...)
with just Promise.resolve()
and Promise.reject()
respectively it catches the errors. Why is that? Aren't both variants asynchronous and thus should work the same way?