64 lines
1.5 KiB
Markdown
64 lines
1.5 KiB
Markdown
# Speaker
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A simple messaging helper that lets you publish and subscribe to messages.
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Callbacks are scheduled as microtasks by default.
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## Interface:
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```
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Speaker(immediate=false)
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// Creates a new speaker.
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Speaker.listen(callback)
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// Registers a callback.
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Speaker.speak(...args)
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// Runs all callbacks with given arguments
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Speaker.silence(callback)
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// Removes a given callback
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```
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## Example
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A simple example:
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```js
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const speaker = new Speaker(true /* run callbacks immediately */)
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speaker.listen(value => console.log(value))
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speaker.listen(value => console.warn(value))
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speaker.speak("This will be logged twice")
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console.log("This message will appear last")
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```
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A slightly more convoluted example:
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```js
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import Speaker from '/speaker.js'
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// A new message that schedules messages as microtasks
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const speaker = new Speaker()
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// A callback that calls messages as functions
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speaker.listen(fn => fn())
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// A shorthand wrapper around the speaker
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const defer = fn => speaker.speak(fn)
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// Defer a function to be called in a microtask
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defer(() => console.log("This message will appear second"))
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console.log("This message will appear first")
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// Defer another function to be called in a microtask
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defer(() => console.log("This message will appear third"))
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// Note: A single speaker will use a single microtask even
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// for multiple messages.
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defer(() => {
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// You can continue pushing messages inside the callback;
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// they will be processed within the same microtask.
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defer(() => console.log("This message will appear last"))
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})
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```
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