A Promise-based API for setTimeout / clearTimeout
npm install await-timeout --save
Just wait some time:
import Timeout from 'await-timeout';
// wait 1000 ms and resolve
await Timeout.set(1000);
// wait 1000 ms and reject with 'Timeout!'
await Timeout.set(1000, 'Timeout!');
Use Timeout
instance inside try...finally
block to make proper cleanup:
import Timeout from 'await-timeout';
const timer = new Timeout();
try {
await Promise.race([
fetch('https://example.com'),
timer.set(1000, 'Timeout!')
]);
} finally {
timer.clear();
}
Without a timer cleanup you may get unexpected effects in you code - as all promises in
Promise.race
are get fulfilled.
Constructs new timeout instance. It does not start timer but creates variable for timer manipulation.
const timer = new Timeout();
Note: having separate
timer
variable is useful for clearing timeout infinally
block
Promise
Starts new timer like setTimeout()
and returns promise. The promise will be resolved after delay
milliseconds:
const timer = new Timeout();
timer.set(1000)
.then(() => console.log('1000 ms passed.'));
If you provide rejectReason
- a timer promise will be rejected with specified reason:
// rejects with Error: Timeout after 1000 ms:
timer.set(1000, 'Timeout after 1000 ms');
// above is actually shortcut for:
timer.set(1000).then(() => Promise.reject(new Error('Timeout after 1000 ms')));
If you need to just wait some time - use static version of .set()
:
await Timeout.set(1000);
Promise
Wraps existing promise with timeout:
async function fetchWithTimeout() {
const promise = fetch('https://example.com');
return Timeout.wrap(promise, 1000, 'Timeout');
}
Actually it is a shortcut for:
async function fetchWithTimeout() {
const timer = new Timeout();
try {
const promise = fetch('https://example.com');
return await Promise.race([
promise,
timer.set(1000, 'Timeout')
]);
} finally {
timer.clear();
}
}
Clears existing timeout like clearTimeout()
.
const timer = new Timeout();
timer.set(1000)
.then(() => console.log('This will never be called, because timeout is cleared on the next line'));
timer.clear();
With ES7 async / await .clear()
can be used in finally
block:
async function foo() {
const timer = new Timeout();
try {
// some async stuff
} finally {
timer.clear();
}
}
?Number|?Timeout
Returns result of setTimeout
call. That is Number
timeout id in browser
and Timeout instance in Node.js.
?Number
Returns last delay value used. Delay is useful for generating reject reason:
const timer = new Timeout();
timer.set(1000, () => new Error(`Timeout: ${timer.delay}`));
Before making this library I've researched several similar packages on Npm. But no one satisfied all my needs together:
setTimeout
/ clearTimeout
. I get used to these functions and would like to have mirror syntax.MIT @ Vitaliy Potapov