There are four places we have special cases based off the DOMProperty
config:
1) DEV-only: ReactDOMUnknownPropertyHook warns for passing booleans to
non-boolean attributes. We just need a simple list of all properties
that are affected by that. We could probably move this in under setProp
instead and have it covered by that list.
2) DEV-only: Hydration. This just needs to read the value from an
attribute and compare it to what we'd expect to see if it was rendered
on the client. This could use some simplification/unification of the
code but I decided to just keep it simple and duplicated since code size
isn't an issue.
3) DOMServerFormatConfig pushAttribute: This just maps the special case
to how to emit it as a HTML attribute.
4) ReactDOMComponent setProp: This just maps the special case to how to
emit it as setAttribute or removeAttribute.
Basically we just have to remember to keep pushAttribute and setProp
aligned. There's only one long switch in prod per environment.
This just turns it all to a giant simple switch statement with string
cases. This is in theory the most optimizable since syntactically all
the information for a hash table is there. However, unfortunately we
know that most VMs don't optimize this very well and instead just turn
them into a bunch of ifs. JSC is best. We can minimize the cost by just
moving common attribute to the beginning of the list.
If we shipped this, maybe VMs will get it together to start optimizing
this case but there's a chicken and egg problem here and the game theory
reality is that we probably don't want to regress. Therefore, I intend
to do a follow up after landing this which reintroduces an object
indirection for simple property aliases. That should be enough to make
the remaining cases palatable. I'll also extract the most common
attributes to the beginning or separate ifs.
Ran attribute-behavior fixture and the table is the same.
This PR has a bunch of surrounding refactoring. See individual commits.
The main change is that we no longer special case `typeof is ===
'string'` as a special case according to the
`enableCustomElementPropertySupport` flag.
Effectively this means that you can't use custom properties/events,
other than the ones React knows about on `<input is="my-input">`
extensions.
This is unfortunate but there's too many paths that are forked in
inconsistent ways since we fork based on tag name. I think __the
solution is to let all React elements set unknown properties/events in
the same way as this flag__ but that's a bigger change than this flag
implies.
Since `is` is not universally supported yet anyway, this doesn't seem
like a huge loss. Attributes still work.
We still support passing the `is` prop and turn that into the
appropriate createElement call.
@josepharhar
Normally we allow any attribute/property on custom elements. However
it's a shared namespace. The `aria-` namespace applies to all generic
elements which are shared with custom elements. So arguably adding
custom extensions there is a really bad idea since it can conflict with
future additions.
It's possible there is a new standard one that's polyfilled by a custom
element but the same issue applies to React in general that we might
warn for very new additions so we just have to be quick on that.
cc @josepharhar
This is a step towards getting rid of the meta programming in
DOMProperty and CSSProperty.
This moves isAttributeNameSafe and isUnitlessNumber to a separate shared
modules.
isUnitlessNumber is now a single switch instead of meta-programming.
There is a slight behavior change here in that I hard code a specific
set of vendor-prefixed attributes instead of prefixing all the unitless
properties. I based this list on what getComputedStyle returns in
current browsers. I removed Opera prefixes because they were [removed in
Opera](https://dev.opera.com/blog/css-vendor-prefixes-in-opera-12-50-snapshots/)
itself. I included the ms ones mentioned [in the original
PR](https://github.com/facebook/react/commit/5abcce534382d85887f3d33475e8e54e3b5d8457).
These shouldn't really be used anymore anyway so should be pretty safe.
Worst case, they'll fallback to the other property if you specify both.
Finally I inline the mustUseProperty special cases - which are also the
only thing that uses propertyName. These are really all controlled
components and all booleans.
I'm making a small breaking change here by treating `checked` and
`selected` specially only on the `input` and `option` tags instead of
all tags. That's because those are the only DOM nodes that actually have
those properties but we used to set them as expandos instead of
attributes before. That's why one of the tests is updated to now use
`input` instead of testing an expando on a `div` which isn't a real use
case. Interestingly this also uncovered that we update checked twice for
some reason but keeping that logic for now.
Ideally `multiple` and `muted` should move into `select` and
`audio`/`video` respectively for the same reason.
No change to the attribute-behavior fixture.
This is not really part of the bindings, it's more part of the package
entry points. /shared/ is not really right neither because it's more
like an isomorphic entry point and not some utility.
We currently throw an error when disableJavaScriptURLs is on and trigger
an error boundary. I kind of thought that's what would happen with CSP
or Trusted Types anyway. However, that's not what happens. Instead, in
those environments what happens is that the error is triggered when you
try to actually visit those links. So if you `preventDefault()` or
something it'll never show up and since the error just logs to the
console or to a violation logger, it's effectively a noop to users.
We can simulate the same without CSP by simply generating a different
`javascript:` url that throws instead of executing the potential attack
vector.
This still allows these to be used - at least as long as you
preventDefault before using them in practice. This might be legit for
forms. We still don't recommend using them for links-as-buttons since
it'll be possible to "Open in a New Tab" and other weird artifacts. For
links we still recommend the technique of assigning a button role etc.
It also is a little nicer when an attack actually happens because at
least it doesn't allow an attacker to trigger error boundaries and
effectively deny access to a page.
This is in line with the refactor I already did on Fizz earlier and
brings Fiber up to a similar structure.
We end up with a lot of extra checks due the extra abstractions we use
to check the various properties. This uses a flatter and more inline
model which makes it easier to see what each property does. The tradeoff
is that a change might need changes in more places.
The general structure is that there's a switch for tag first, then a
switch for each attribute special case, then a switch for the value. So
it's easy to follow where each scenario will end up and there shouldn't
be any unnecessary code executed along the way.
My goal is to eventually get rid of the meta-programming in DOMProperty
and CSSProperty but I'm leaving that in for now - in line with Fizz.
My next step is moving around things a bit in the diff/commit phases.
This is the first step to more refactors for perf and size, but also
because I'm adding more special cases so I need to have a flatter
structure that I can reason about for those special cases.
I'm trying to get rid of all meta programming in the module scope so
that closure can do a better job figuring out cyclic dependencies and
ability to reorder.
This is converting a lot of the patterns that assign functions
conditionally to using function declarations instead.
```
let fn;
if (__DEV__) {
fn = function() {
...
};
}
```
->
```
function fn() {
if (__DEV__) {
...
}
}
```
These used to be used by partial render.
ReactDOMDispatcher ended up not being used in this way.
Move shared DOM files to client. These are only used by client
abstractions now. They're inlined in the Fizz code so they're no longer
shared.
We disallow empty strings for `href` and `src` since they're common
mistakes that end up loading the current page as a preload, image or
link. We also disallow it for `action`. You have to pass `null` which is
the same.
However, for `formAction` passing `null` is not the same as passing
empty string. Passing empty string overrides the form's action to be the
current page even if the form's action was set to something else.
There's no easy way to express the same thing `#` show up in the user
visible URLs and `?` clears the search params.
Since this is also not a common mistake, we can just allow this.
## Do not hoist elements with `itemProp`
In HTML `itemprop` signifies a property of an `itemscope` with respect
to the Microdata spec
(https://html.spec.whatwg.org/multipage/microdata.html#microdata)
additionally `itemprop` is valid on any tag and can even make some tags
that are otherwise invalid in the `<body>` valid there (`<meta>` for
instance).
Originally I tried an approach where if you rendered something otherwise
hoistable inside an `itemscope` it would not hoist if it had an
`itemprop`. This meant that some components with `itemprop` could hoist
(if they were not scoped, which is generally invalid microdata
implementation). However the problem is things that do hoist, hoist into
the head and body and these tags can have an `itemscope`. This creates a
ton of ambiguity when trying to hydrate in these hoist scopes because we
can't know for certain whether a DOM node we find there was hoisted or
not even if it has an `itemprop` attribute. There are other scenarios
too that have abiguous semantics like rendering a hoistable with
`itemProp` outside of `<html itemScope={true>`. Is it fair to embed that
hoistable inside that itemScope even though it was defined outside?
To simplify the situation and disambiguate I dropped the `itemscope`
portion from the implementation and now any host component that could
normally be hoisted will not hoist if it has an `itemProp` prop.
In addition to the changes made for `itemProp` this PR also modifies
part of the hydration implementation to be more tolerant of tags
injected by 3rd parties. This was opportunistically done when we needed
to have context information like `inItemScope` but with the most recent
implementation that has been removed. I have however left the hydration
changes in place as it is a goal to make React handle hydrating the
entire Document even when we cannot control whether 3rd parties are
going to inject tags that React will not render but are also not
hoistables
-------
##### Original Description when we considered tracking itemScope
>One recent decision was to make elements using the `itemProp` prop not
hoistable if they were inside and itemScope. This better fits with
Microdata spec which allows for meta tags and other tag types usually
reserved for the `<head>` to be used in the `<body>` when using
itemScope.
>
>To implement this a number of small changes were necessary
>
>1. HostContext in prod needed to expand beyond just tracking the
element namespace for new element creation. It now tracks whether we are
in an itemScope. To keep this efficient it is modeled as a bitmask.
>2. To disambiguate what is and is not a potential instance in the DOM
for hoistables the hydration algo was updated to skip past non-matching
instances while attempting to claim the instance rather than ahead of
time (getNextHydratable).
>3. React will not consider an itemScope on `<html>`, `<head>`, or
`<body>` as a valid scope for the hoisting opt-out. This is important as
an invariant so we can make assumptions about certain tags in these
scopes. This should not be a functional breaking change because if any
of these tags have an `itemScope` then it can just be moved into the
first node inside the `<body>`
>
>Since we were already updating the logic for hydration to better
support `itemScope` opt-out I also changed the hydration behavior for
suspected 3rd party nodes in `<head>` and `<body>`. Now if you are
hydrating in either of those contexts hydration will skip past any
non-matching nodes until it finds a match. This allows 3rd party scripts
and extensions to inject nodes in either context that React does not
expect and still avoid a hydration mismatch.
>
>This new algorithm isn't perfect and it is possible for a mismatch to
occur. The most glaring case may be if a 3rd party script prepends a
`<div>` into `<body>` and you render a `<div>` in `<body>` in your app.
there is nothing to signal to React that this div was 3rd party so it
will claim is as the hydrated instance and hydration will almost
certainly fail immediately afterwards.
>
>The expectation is that this is rare and that if falling back to client
rendering is transparent to the user then there is not problem here. We
will continue to evaluate this and may change the hydration matching
algorithm further to match user and developer expectations
Adds two new ReactDOM methods
### `ReactDOM.prefetchDNS(href: string)`
In SSR this method will cause a `<link rel="dns-prefetch" href="..." />`
to flush before most other content both on intial flush (Shell) and late
flushes. It will only emit one link per href.
On the client, this method will case the same kind of link to be
inserted into the document immediately (when called during render, not
during commit) if there is not already a matching element in the
document.
### `ReactDOM.preconnect(href: string, options?: { crossOrigin?: string
})`
In SSR this method will cause a `<link rel="dns-prefetch" href="..."
[corssorigin="..."] />` to flush before most other content both on
intial flush (Shell) and late flushes. It will only emit one link per
href + crossorigin combo.
On the client, this method will case the same kind of link to be
inserted into the document immediately (when called during render, not
during commit) if there is not already a matching element in the
document.
## Summary
CSS has a new property called `scale` (`scale: 2` is a shorthand for
`transform: scale(2)`).
In vanilla JavaScript, we can do the following:
```js
document.querySelector('div').scale = 2;
```
which will make the `<div>` twice as big. So in JavaScript, it is
possible to pass a plain number.
However, in React, the following does not work currently:
```js
<div style={{scale: 2}}>
```
because `scale` is not in the list of unitless properties. This PR adds
`scale` to the list.
## How did you test this change?
I built `react` and `react-dom` from source and copied it into the
node_modules of my project and verified that now `<div style={{scale:
2}}>` does indeed work whereas before it did not.
## Hoistables
In the original implementation of Float, all hoisted elements were
treated like Resources. They had deduplication semantics and hydrated
based on a key. This made certain kinds of hoists very challenging such
as sequences of meta tags for `og:image:...` metadata. The reason is
each tag along is not dedupable based on only it's intrinsic properties.
two identical tags may need to be included and hoisted together with
preceding meta tags that describe a semantic object with a linear set of
html nodes.
It was clear that the concept of Browser Resources (stylesheets /
scripts / preloads) did not extend universally to all hositable tags
(title, meta, other links, etc...)
Additionally while Resources benefit from deduping they suffer an
inability to update because while we may have multiple rendered elements
that refer to a single Resource it isn't unambiguous which element owns
the props on the underlying resource. We could try merging props, but
that is still really hard to reason about for authors. Instead we
restrict Resource semantics to freezing the props at the time the
Resource is first constructed and warn if you attempt to render the same
Resource with different props via another rendered element or by
updating an existing element for that Resource.
This lack of updating restriction is however way more extreme than
necessary for instances that get hoisted but otherwise do not dedupe;
where there is a well defined DOM instance for each rendered element. We
should be able to update props on these instances.
Hoistable is a generalization of what Float tries to model for hoisting.
Instead of assuming every hoistable element is a Resource we now have
two distinct categories, hoistable elements and hoistable resources. As
one might guess the former has semantics that match regular Host
Components except the placement of the node is usually in the <head>.
The latter continues to behave how the original implementation of
HostResource behaved with the first iteration of Float
### Hoistable Element
On the server hoistable elements render just like regular tags except
the output is stored in special queues that can be emitted in the stream
earlier than they otherwise would be if rendered in place. This also
allow for instance the ability to render a hoistable before even
rendering the <html> tag because the queues for hoistable elements won't
flush until after we have flushed the preamble (`<DOCTYPE
html><html><head>`).
On the client, hoistable elements largely operate like HostComponents.
The most notable difference is in the hydration strategy. If we are
hydrating and encounter a hoistable element we will look for all tags in
the document that could potentially be a match and we check whether the
attributes match the props for this particular instance. We also do this
in the commit phase rather than the render phase. The reason hydration
can be done for HostComponents in render is the instance will be removed
from the document if hydration fails so mutating it in render is safe.
For hoistables the nodes are not in a hydration boundary (Root or
SuspenseBoundary at time of writing) and thus if hydration fails and we
may have an instance marked as bound to some Fiber when that Fiber never
commits. Moving the hydration matching to commit ensures we will always
succeed in pairing the hoisted DOM instance with a Fiber that has
committed.
### Hoistable Resource
On the server and client the semantics of Resources are largely the same
they just don't apply to title, meta, and most link tags anymore.
Resources hoist and dedupe via an `href` key and are ref counted. In a
future update we will add a garbage collector so we can clean up
Resources that no longer have any references
## `<style>` support
In earlier implementations there was no support for <style> tags. This
PR adds support for treating `<style href="..."
precedence="...">...</style>` as a Resource analagous to `<link
rel="stylesheet" href="..." precedence="..." />`
It may seem odd at first to require an href to get Resource semantics
for a style tag. The rationale is that these are for inlining of actual
external stylesheets as an optimization and for URI like scoping of
inline styles for css-in-js libraries. The href indicates that the key
space for `<style>` and `<link rel="stylesheet" />` Resources is shared.
and the precedence is there to allow for interleaving of both kinds of
Style resources. This is an advanced feature that we do not expect most
app developers to use directly but will be quite handy for various
styling libraries and for folks who want to inline as much as possible
once Fizz supports this feature.
## refactor notes
* HostResource Fiber type is renamed HostHoistable to reflect the
generalization of the concept
* The Resource object representation is modified to reduce hidden class
checks and to use less memory overall
* The thing that distinguishes a resource from an element is whether the
Fiber has a memoizedState. If it does, it will use resource semantics,
otherwise element semantics
* The time complexity of matching hositable elements for hydration
should be improved
The old version of prettier we were using didn't support the Flow syntax
to access properties in a type using `SomeType['prop']`. This updates
`prettier` and `rollup-plugin-prettier` to the latest versions.
I added the prettier config `arrowParens: "avoid"` to reduce the diff
size as the default has changed in Prettier 2.0. The largest amount of
changes comes from function expressions now having a space. This doesn't
have an option to preserve the old behavior, so we have to update this.
This enables the "exact_empty_objects" setting for Flow which makes
empty objects exact instead of building up the type as properties are
added in code below. This is in preparation to Flow 191 which makes this
the default and removes the config.
More about the change in the Flow blog
[here](https://medium.com/flow-type/improved-handling-of-the-empty-object-in-flow-ead91887e40c).
This setting is an incremental path to the next Flow version enforcing
type annotations on most functions (except some inline callbacks).
Used
```
node_modules/.bin/flow codemod annotate-functions-and-classes --write .
```
to add a majority of the types with some hand cleanup when for large
inferred objects that should just be `Fiber` or weird constructs
including `any`.
Suppressed the remaining issues.
Builds on #25918
Flow introduced a new syntax to annotated the context type of a
function, this tries to update the rest and add 1 example usage.
- 2b1fb91a55 already added the changes
required for eslint.
- Jest transform is updated to use the recommended `hermes-parser` which
can parse current and Flow syntax and will be updated in the future.
- Rollup uses a new plugin to strip the flow types. This isn't ideal as
the npm module is deprecated in favor of using `hermes-parser`, but I
couldn't figure out how to integrate that with Rollup.
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## Summary
- Fixes https://github.com/facebook/react/issues/25682
## How did you test this change?
I tried this but it didn't work
```
yarn build --type=UMD_DEV react/index,react-dom && cd fixtures/attribute-behavior && yarn install && yarn start
```
Co-authored-by: eps1lon <silbermann.sebastian@gmail.com>
stacked on https://github.com/facebook/react/pull/25514
This PR adds support for any type of Link as long as it has a string rel
and href and does not include an onLoad or onError property.
The semantics for generic link resources matches other head resources,
they will be inserted and removed as their ref counts go positive and
back to zero.
Keys are based on rel, href, sizes, and media.
on the server preconnect and prefetch-dns are privileged and will emit
near the start of the stream.
Adds a category of Resources of type `head` which will be used to track
the tags that go into the <head>
Currently only implements for `<title>`.
titles are keyed off their textContent so each time the title changes a
new resource will be created. Currently insertion is done by prepending
in the <head>. The argument here is that the newest title should "win"
if there are multiple rendered. This also helps when a navigation or
update causes a server rendered title to hang around but it is not the
most recent one.
* Facebook -> Meta in copyright
rg --files | xargs sed -i 's#Copyright (c) Facebook, Inc. and its affiliates.#Copyright (c) Meta Platforms, Inc. and affiliates.#g'
* Manual tweaks
* float enhance!!!
Support preinit as script
Support resources from async scripts
Support saving the precedence place when rendering the shell
There was a significant change to the flushing order of resources which follows the general principal of...
1. stuff that blocks display
2. stuff that we know will be used
3. stuff that was explicitly preloaded
As a consequence if you preinit a style now it won't automatically flush in the shell unless you actually depend on it in your tree. To avoid races with precedence order we now emit a tag that saves the place amongst the precedence hierarchy so late insertions still end up where they were intended
There is also a novel hydration pathway for certain tags. If you render an async script with an onLoad or onError it will always treat it like an insertion rather than a hydration.
* restore preinit style flushing behavior and nits
* [Fizz/Float] Float for stylesheet resources
This commit implements Float in Fizz and on the Client. The initial set of supported APIs is roughly
1. Convert certain stylesheets into style Resources when opting in with precedence prop
2. Emit preloads for stylesheets and explicit preload tags
3. Dedupe all Resources by href
4. Implement ReactDOM.preload() to allow for imperative preloading
5. Implement ReactDOM.preinit() to allow for imperative preinitialization
Currently supports
1. style Resources (link rel "stylesheet")
2. font Resources (preload as "font")
later updates will include support for scripts and modules
This lets us share it with react-server-dom-webpack while still having a
dependency on react-dom. It also makes somewhat sense from a bundling
perspective since react-dom is an external to itself.
Sebastian Markbåge
Josh Story
Jonny Burger
Jan Kassens
Aravind D
Steven
Ikko Ashimine
Andrew Clark