54 lines
1.3 KiB
Markdown
54 lines
1.3 KiB
Markdown
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change-emitter
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==============
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[](https://travis-ci.org/acdlite/change-emitter)
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[](https://www.npmjs.com/package/change-emitter)
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Listen for changes. Like an event emitter that only emits a single event type. Really tiny.
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I extracted this from Redux's `createStore()` because I found it to be useful in other contexts. Use it where you want the most minimal event subscription implementation possible.
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## Usage
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```js
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import { createChangeEmitter } from 'change-emitter'
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const emitter = createChangeEmitter()
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// Called `listen` instead of `subscribe` to avoid confusion with observable spec
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const unlisten = emitter.listen((...args) => {
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console.log(args)
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})
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emitter.emit(1, 2, 3) // logs `[1, 2, 3]`
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unlisten()
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emitter.emit(4, 5, 6) // doesn't log
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```
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## Larger example
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Here's a (partial) implementation of Redux's `createStore`:
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```js
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const createStore = (reducer, initialState) => {
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let state = initialState
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const emitter = createChangeEmitter()
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function dispatch(action) {
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state = reducer(state, action)
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emitter.emit()
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return action
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}
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function getState() {
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return state
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}
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return {
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dispatch,
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getState,
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subscribe: emitter.listen
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}
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}
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```
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