tl;dr: Some minor changes which make this release safe to upgrade for everyone!
Another week, another Preact release! It seems like the previous one wasn't too long ago, but there are already so many cool changes in master that we're eager to bundle them in a neat release!
Much improved conditional rendering
One insanely cool and very important change was done by @andrewiggins, who woke up one day and found a very elegant solution to handling conditionally rendered elements. Most virtual-dom-based frameworks mark a falsy result with some sort placeholder (sometimes referred to as "holes"), so that the diffing algorithm can ensure that elements are not moved around needlessly.
It's not just for performance though as they are some real world consequences to moving nodes around. The most common annoyance is <input>-elements losing focus whenever a parent is moved. With this change we are pretty confident that we squashed all known issues on that front 👍
Improved SVG attribute casing
SVG also received a big change by @steveharrison . It's his first contribution Preact and he already knocked it out of the park with an excellent PR. HE went through the whole SVG spec and noticed that we didn't match some of the weird casings of SVG-Attributes properly and his PR remedies that beautifully! 💯
Preact sightings
@pksjce finished her YouTube series where she reads through a portion of the Preact source code. With that she helped us tremendously in spotting areas in code which lacked comments and finally pushed us to create a proper "Contributing" guide. If you are considering contributing to Preact, this short document is well worth a read as it contains an overview of the repo's structure and answers for the most common questions regarding our code. That said if you feel like something is missing or you do have troubles understanding some sections of the source, please reach out to us! We're here to help and feedback about friction points is crucial to making Preact better for everyone 👍
Checking our official website you may have noticed some slight changes here and there. They're mostly to simplify navigation or to give our docs a more fitting structure. The long term plan is to integrate our learnings about the most common support questions we get and fill in those spots. @NJalal7 spotted a few of those areas and even found a bug in Preact in the process that we we're promptly able to fix 🙌
Thank you so much to everyone who contributed code, helped us in narrowing down issues or participated in making Preact even better. Preact wouldn't be were it is now without you all ❤️
Features
- Compat: Add
isPropagationStoppedfn to event (#2378, thanks @reznord) - Compat: Add
isDefaultPreventedfn to event (#2377, thanks @teodragovic) - Large performance boost in
preact/debug(#2362, thanks @developit)
Bug Fixes
- Fix
event.isPropagationStopped()(#2380, thanks @38elements) - Fixed SVG attribute names not being converted to the correct attribute names in the DOM. (#2366, thanks @steveharrison)
- Fix incorrect warning on
setStateinsidecomponentWillMount(#2367, thanks @marvinhagemeister) - Fix static hydration (#2365, thanks @JoviDeCroock)
- Fix hook outside of component test (#2359, thanks @JoviDeCroock)
- Remove warning for
useEffect/useLayoutEffect(#2358, thanks @JoviDeCroock) - Improve
nullplaceholder DOM placement (#2355, thanks @andrewiggins)
Typings
- Fix
options.eventtype definition (#2381, thanks @38elements)
Maintenance
- Add comment to clarify seemingly redundant string concatenation (#2369, thanks @mhmdanas)
- Rename some variables to increase legibility (#2361, thanks @andrewiggins)
- Combine searches in
excessDomChildreninto the same code block (#2356, thanks @andrewiggins) - Fix failing test by defaulting to empty array (#2353, thanks @JoviDeCroock)
- Add new test file for
nullplaceholders (#2352, thanks @andrewiggins)