You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
89 lines
2.5 KiB
Markdown
89 lines
2.5 KiB
Markdown
# @joepie91/promise-delay-every
|
|
|
|
A function for writing *one per N amount of time* rate-limiting implementations.
|
|
|
|
When called, it returns a 'delayer' function. This delayer function can be called repeatedly; every time it is called, it returns a Promise that resolves `delay` milliseconds further into the future. The first time it is called, it resolves immediately.
|
|
|
|
So for example, if you specify a `delay` of 2000 milliseconds, the Promise returned from the first call will resolve immediately; the Promise returned from the second call will resolve after 2 seconds, the Promise resolved from the third call will resolve after 4 seconds, and so on.
|
|
|
|
All of these times are relative to the first call you make - so in the above example, there are 2 seconds between every resolution:
|
|
|
|
```
|
|
0ms Call 1
|
|
0ms Resolve 1
|
|
2ms Call 2
|
|
3ms Call 3
|
|
5ms Call 4
|
|
2000ms Resolve 2
|
|
4000ms Resolve 3
|
|
6000ms Resolve 4
|
|
```
|
|
|
|
If you wait longer than the delay to call the delayer function again, the returned Promise will resolve immediately and that time becomes the new base time for future delays:
|
|
|
|
```
|
|
0ms Call 1
|
|
0ms Resolve 1
|
|
2ms Call 2
|
|
2000ms Resolve 2
|
|
... time passes, beyond the 2000ms delay ...
|
|
7400ms Call 3
|
|
7400ms Resolve 3
|
|
7402ms Call 4
|
|
9400ms Resolve 4
|
|
```
|
|
|
|
## Example
|
|
|
|
See also `example.js` for a runnable version. This example uses Bluebird for `Promise.try` (read [this article](http://cryto.net/~joepie91/blog/2016/05/11/what-is-promise-try-and-why-does-it-matter/) to understand why), but Bluebird is not required to use this module.
|
|
|
|
```js
|
|
"use strict";
|
|
|
|
const Promise = require("bluebird");
|
|
const promiseDelayEvery = require("@joepie91/promise-delay-every");
|
|
|
|
let delayer = promiseDelayEvery(2000);
|
|
|
|
return Promise.try(() => {
|
|
return delayer();
|
|
}).then(() => {
|
|
// Logs immediately after running
|
|
console.log("Hello world 1");
|
|
|
|
return delayer();
|
|
}).then(() => {
|
|
// Logs 2 seconds after running
|
|
console.log("Hello world 2");
|
|
|
|
return delayer();
|
|
}).then(() => {
|
|
// Logs 4 seconds after running
|
|
console.log("Hello world 3");
|
|
});
|
|
```
|
|
|
|
## API
|
|
|
|
### promiseDelayEvery(delay)
|
|
|
|
Returns a new `delayer` function.
|
|
|
|
- __delay:__ The delay as a number, in millseconds.
|
|
|
|
### delayer()
|
|
|
|
Returns a new Promise that will resolve at the next scheduled interval, according to the algorithm described at the top of this documentation.
|
|
|
|
The Promise will never reject.
|
|
|
|
## Changelog
|
|
|
|
### v1.0.1 (February 17, 2020)
|
|
|
|
- Fixed repository URL in package.json
|
|
|
|
### v1.0.0 (April 23, 2019)
|
|
|
|
Initial release.
|