91 lines
2.2 KiB
Markdown
91 lines
2.2 KiB
Markdown
|
# p-limit [](https://travis-ci.org/sindresorhus/p-limit)
|
||
|
|
|
||
|
|
> Run multiple promise-returning & async functions with limited concurrency
|
||
|
|
|
||
|
|
|
||
|
|
## Install
|
||
|
|
|
||
|
|
```
|
||
|
|
$ npm install p-limit
|
||
|
|
```
|
||
|
|
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
|
||
|
|
```js
|
||
|
|
const pLimit = require('p-limit');
|
||
|
|
|
||
|
|
const limit = pLimit(1);
|
||
|
|
|
||
|
|
const input = [
|
||
|
|
limit(() => fetchSomething('foo')),
|
||
|
|
limit(() => fetchSomething('bar')),
|
||
|
|
limit(() => doSomething())
|
||
|
|
];
|
||
|
|
|
||
|
|
(async () => {
|
||
|
|
// Only one promise is run at once
|
||
|
|
const result = await Promise.all(input);
|
||
|
|
console.log(result);
|
||
|
|
})();
|
||
|
|
```
|
||
|
|
|
||
|
|
|
||
|
|
## API
|
||
|
|
|
||
|
|
### pLimit(concurrency)
|
||
|
|
|
||
|
|
Returns a `limit` function.
|
||
|
|
|
||
|
|
#### concurrency
|
||
|
|
|
||
|
|
Type: `number`<br>
|
||
|
|
Minimum: `1`
|
||
|
|
|
||
|
|
Concurrency limit.
|
||
|
|
|
||
|
|
### limit(fn, ...args)
|
||
|
|
|
||
|
|
Returns the promise returned by calling `fn(...args)`.
|
||
|
|
|
||
|
|
#### fn
|
||
|
|
|
||
|
|
Type: `Function`
|
||
|
|
|
||
|
|
Promise-returning/async function.
|
||
|
|
|
||
|
|
#### args
|
||
|
|
|
||
|
|
Any arguments to pass through to `fn`.
|
||
|
|
|
||
|
|
Support for passing arguments on to the `fn` is provided in order to be able to avoid creating unnecessary closures. You probably don't need this optimization unless you're pushing a *lot* of functions.
|
||
|
|
|
||
|
|
### limit.activeCount
|
||
|
|
|
||
|
|
The number of promises that are currently running.
|
||
|
|
|
||
|
|
### limit.pendingCount
|
||
|
|
|
||
|
|
The number of promises that are waiting to run (i.e. their internal `fn` was not called yet).
|
||
|
|
|
||
|
|
|
||
|
|
## FAQ
|
||
|
|
|
||
|
|
### How is this different from the [`p-queue`](https://github.com/sindresorhus/p-queue) package?
|
||
|
|
|
||
|
|
This package is only about limiting the number of concurrent executions, while `p-queue` is a fully featured queue implementation with lots of different options, introspection, and ability to pause and clear the queue.
|
||
|
|
|
||
|
|
|
||
|
|
## Related
|
||
|
|
|
||
|
|
- [p-queue](https://github.com/sindresorhus/p-queue) - Promise queue with concurrency control
|
||
|
|
- [p-throttle](https://github.com/sindresorhus/p-throttle) - Throttle promise-returning & async functions
|
||
|
|
- [p-debounce](https://github.com/sindresorhus/p-debounce) - Debounce promise-returning & async functions
|
||
|
|
- [p-all](https://github.com/sindresorhus/p-all) - Run promise-returning & async functions concurrently with optional limited concurrency
|
||
|
|
- [More…](https://github.com/sindresorhus/promise-fun)
|
||
|
|
|
||
|
|
|
||
|
|
## License
|
||
|
|
|
||
|
|
MIT © [Sindre Sorhus](https://sindresorhus.com)
|