callforth
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A tiny utility library to conveniently replace callbacks with Promises.
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# Callforth :running:
[](https://badge.fury.io/js/callforth)
A tiny utility library to replace callbacks with Promises where possible.
**Don't callback, callforth!**
It simply includes a hand-full of functions I see myself re-implementing in nearly every project.
So I might as well put them in a package.
Do things like:
```js
await timeout(3000)
```
```js
await eventOn(videoElement, "loadeddata")
```
```js
const message = await eventOn(webWorker, "message")
```
## Install :package:
```sh
npm install callforth
```
Now you can:
```js
import { eventOn, timeout, polling } from "callforth"
```
Alternatively, include [this script](https://unpkg.com/callforth/dist/callforth.umd.js) and:
```html
<script src="./path/to/callforth.umd.js"></script>
<script>
const { eventOn, timeout, polling } = window.callforth
</script>
```
## API :eyes:
### `eventOn`
```js
const payload = await eventOn(target, successEvent, errorEvent)
```
#### Parameters
* _target_ : `EventTarget` - any object you can call `addEventListener` on.
* _successEvent_ : `string` - name of the event you want to await.
* _errorEvent_ : `string` (optional) - if this event fires, the promise is rejected.
#### Return Value
* `Promise<any>` - wraps callback result (callbacks first argument)
### `timeout`
```js
await timeout(delay)
```
#### Parameters
* _delay_ : `int` - milliseconds after which the Promise should resolves.
#### Return Value
* `Promise<void>`
### `polling`
```js
await polling(predicate, { maxTries, interval })
```
#### Parameters
* _predicate_ : `any -> boolean` - delay in milliseconds after which the Promise should resolve.
* _options_ : `object` (optional)
* _maxTries_ : `int` (default = 10) - maximum number of times to call predicate before giving up.
* _interval_ : `int` (default = 10) - delay in milliseconds between calls of predicate.
#### Return Value
* `Promise<void>`
## More Examples
```js
async function loadScript(url) {
let script = document.createElement("script")
script.src = url
await eventOn(script, "loaded")
}
```
```js
async function primesLessThen(number) {
primeWorker.postMessage(number)
const result = await eventOn(primeWorker, "message")
return result
}
```