defer reject
Defer rejection explicitly until a catch handler is attached.
Install
$ npm i defer-rejectUsage
import { deferReject } from 'defer-reject';
async function work1()
{
await new Promise((_resolve, reject) => {
setTimeout(() => {
reject(new Error('rejected'))
}, 1000)
});
}
async function work2()
{
return new Promise(resolve => setTimeout(resolve, 2000));
}
async function work()
{
try{
const work1_result = deferReject(work1());
await work2();
return await work1_result;
}catch(e){
console.log("Caught:", e);
}
}
work();API
deferReject<T>(promise: Promise<T>): Promise<T>: defer rejection of a promise until a catch handler is attached(awaited or catch(onrejected) or then(onfulfilled, onrejected) is called).
RejectDeferredPromise<T>: a promise with deferred rejection. constructor is same as Promise<T>
W?
After node v15.0.0, unhandled rejections will emit unhandledRejection events by default. If an unhandledRejection event is not handled, it will throw an error and exit the process.
try {
// if this rejects before work2 is finished, the process will exit
const p1: Promise<T> = work1();
await work2();
return await p1;
}
...With the deferReject() function, rejection will be deferred until the promise is awaited or catch(onrejected) or then(onfulfilled, onrejected) is called. This will prevent the process from exiting without changing --unhandled-rejections.
try {
// exception will be caught by catch block
const p1: Promise<T> = deferReject(work1());
await work2();
return await p1;
}
...