89 lines
2.3 KiB
HTML
89 lines
2.3 KiB
HTML
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<link rel="stylesheet" href="style.css">
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<script type="module" src="codeblock.js"></script>
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<script type="module" src="scrollToTop.js"></script>
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<scroll-to-top>
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</scroll-to-top>
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<a class="back" href="..">Module Index</a>
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<h1 class="js module">speaker.js</h1>
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<code-block>import {Speaker} from 'speaker.js'</code-block>
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<section>
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<h2>Description</h2>
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<p>
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A publish/subscribe helper class that uses micro-tasks to relay messages to many subscribers.
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</p>
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</section>
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<section>
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<h2>Example</h2>
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<code-block>
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const speaker = new Speaker()
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speaker.listen(message => { document.title = message })
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speaker.listen(message => { console.log(`Message received: ${message}`) })
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speaker.speak("New page title")
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console.log("This line runs before any of the callbacks")
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</code-block>
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<p>
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Note that the callbacks don't run immediately.
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They are scheduled to a micro-task to be called later on.
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</p>
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</section>
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<section>
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<h2>Methods</h2>
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<dl>
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<dt><code>new Speaker(...initial) : Speaker</code></dt>
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<dd>
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Constructs a new speaker.
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All arguments passed to the constructor will be retained and returned
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by any call to <code>listen</code> before the first time <code>speak</code>
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is called.
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</dd>
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<dt><code>Speaker.listen(callback : (...args) => undefined) : [...args]</code></dt>
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<dd>
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Registers a callback to be called on every new message.
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Returns an array containing the retained arguments of the last message.
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</dd>
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<dt><code>Speaker.speak(...args)</code></dt>
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<dd>
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Relays a message of zero or more arguments to all registered callbacks.
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As mentioned above, callbacks will not be called immediately, but scheduled in a new micro-task.
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The arguments are retained until <code>speak</code> is called again.
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</dd>
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<dt><code>Speaker.forget(callback)</code></dt>
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<dd>
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Removes a single callback function from its list of callbacks.
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</dd>
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<dt><code>Speaker.silence()</code></dt>
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<dd>
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Clears the list of callbacks completely.
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</dd>
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</dl>
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</section>
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<section>
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<h2>Immediate Speaker</h2>
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<p>
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Additionally, the module exposts the <code>ImmediateSpeaker</code> class,
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which does the exact same as a normal speaker,
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but executes its callbacks immediately instead of scheduling a micro-task.
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</p>
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<p>
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The API is the <em>exact same</em> as a normal <code>Speaker</code>.
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</p>
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</section>
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