Compose: Documentation: Document withGlobalEvents #15175
Conversation
aduth
added
[Type] Developer Documentation
aduth
requested review from
ajitbohra,
gziolo,
jorgefilipecosta,
noisysocks,
talldan and
youknowriad
as code owners
| create or update a window event handler to invoke the callback when an event | ||
| occurs. On behalf of the consuming developer, the higher-order component | ||
| manages unbinding when the component unmounts, and binding at most a single | ||
| event handler for the entire application. |
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Interesting. Isn't that a built in feature of addEventListener to bind once at most?
The event listener list will not contain multiple event listeners with equal type, callback, and capture, as add an event listener prevents that.
https://dom.spec.whatwg.org/#dom-eventtarget-addeventlistener
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The key words there being "equal [..] callback". Since function() {} !== function() {}, it's not reused.
Try in the console, for example:
[ ...Array( 5 ) ].forEach( ( v, i ) => document.addEventListener( 'click', () => console.log( 'click' + i ) ) )
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Interesting. Isn't that a built in feature of addEventListener to bind once at most?
While it's not really relevant for change here, the question does get me wondering whether it really matters to consolidate to a single event handler. I'm trying to recall from the original implementation (#5730) whether I'd thought this was some sort of performance enhancement (i.e. one 'scroll' handler on the window rather than one for every component) and if that was the case, whether there's actually any truth to the consolidation being an optimization. I might expect a browser with its low-level language code could iterate to invoke individual callbacks of addEventListener faster than we could iterate to invoke the Listener callbacks here in JavaScript.
This pull request seeks to add missing documentation for the
withGlobalEventshigher-order component creator.Testing Instructions:
Verify by rendered output of "Files changed" tab that produced documentation is sensible.
There are only documentation changes. Thus, there is no expected impact on application runtime.