Waitup - Delays and retries within Promise chains
Wait up for whatever.
Waitup provides delays and retries within Promise chains.
Installation
Waitup was written for Node.js 4+.
npm install --save waitup
Usage
There are several ways of using Waitup.
Simple Delays
Waitup can be used to introduce a delay before continuing within a Promise chain.
let waitup = require('waitup');
waitup(5000)
.then(() => {
console.log('Waited approximately 5 seconds...')
return waitup({
delay: 2500
});
})
.then(() => {
console.log('Waited approximately 2.5 seconds this time...');
});
Calling waitup returns a Promise. The default delay is 1 second (1000 milliseconds).
Wait Up For Completion
Waitup can also be configured to wait for the completion of an operation. A callback
can be provided to waitup's for option. This callback accepts a single argument
for the waitee. When the operation is considered complete, return the value of
waitee.done(). An optional result can be provided to waitee.done() to forward
to the resolved promise.
let someResult = false;
setTimeout(() => someResult = true, 5000);
waitup({
for: waitee => {
if (someResult === true) {
return waitee.done('example result');
}
console.log('someResult not true yet');
},
delay: 500
})
.then(exampleResult => {
console.log('Waitee is done waiting!');
console.log(`Result: ${exampleResult}`);
});
Additionally, a number of retries can be configured before rejection. Set the
number of allowable retries to waitup's retries option.
let someResult = false;
waitup({
for: waitee => {
if (someResult === true) {
return waitee.done();
}
console.log('someResult not true yet');
},
retries: 5,
delay: 500
})
.then(() => {
console.log('This will never succeed...');
})
.catch(error => {
console.log(error.stack);
});
If retries are not configured, or if the waitee.done() value is never returned,
the application could run indefinitely.
Examples
See more examples in the examples directory.
Logo
Waitup's initial logo was designed by scorpion6 on Fiverr. Font used is Lato Light.
License
This software is licensed under the MIT License. View the license.
Copyright © 2015 Michael K. Squires