Update changelog for unreleased 16.0 changes #10730

flarnie · 2017-09-18T06:03:20Z

what is the change?:

Copies most content from React 16 RC #10294, summarizing and adding links in a couple of cases. Tried to group things in a logical way.
Adds a couple of items under "Removed deprecations " and "New helpful warnings ". These sections are probably not complete, but this is a good start.

why make this change?:
So that we are ready to go when the 16.0 release is green-lighted. 🚦✨🚀🎆

test plan:
Visual inspection

issue:
#8854

**what is the change?:** Added an 'unreleased' section to the changelog with info from facebook#10294 **why make this change?:** To get things set for the 16.0 release. **test plan:** Visual inspection **issue:** facebook#8854

NE-SmallTown · 2017-09-18T07:45:48Z

Cool! Could we add corresponding jsfiddle demo and why we did this(or issue permalink) of per change?

gaearon · 2017-09-18T11:35:39Z

CHANGELOG.md

+- **The deprecations introduced in 15.x have been removed from the core package.** React.createClass is now available as create-react-class, React.PropTypes as prop-types, React.DOM as react-dom-factories, react-addons-test-utils as react-dom/test-utils, and shallow renderer as react-test-renderer/shallow. See [15.5.0](https://facebook.github.io/react/blog/2017/04/07/react-v15.5.0.html) and [15.6.0](https://facebook.github.io/react/blog/2017/06/13/react-v15.6.0.html) blog posts for instructions on migrating code and automated codemods.
+
+### New helpful warnings
+


Let's remove this section. There is quite a bit of new (or improved) warnings in 16. These are just the ones added between RCs and IMO having them here is more confusing than skipping the whole section.

Thanks - will remove for now.

What if I got the diff in warnings between 15 and 16 and documented the changes? Could be a follow-up.

koba04 · 2017-09-19T02:45:47Z

CHANGELOG.md

+    Click to see more.
+  </summary>
+
+### JS Environment Requirements


What about requestAnimationFrame?

flarnie · 2017-09-20T15:44:55Z

Cool! Could we add corresponding jsfiddle demo and why we did this(or issue permalink) of per change?

@NE-SmallTown I had originally written a more traditional CHANGELOG with a PR and contributor permalink per change, like at the bottom of the 16.0RC issue.

Discussing this with the team, we decided to omit permalinks to specific PRs for most of these items, because the changes in 16.0 are each is generally pretty big and include work from many PRs and contributors.

Regarding a jsfiddle demo - has that been a typical part of major release changelogs? I think the blog posts I linked to should cover that sort of detail for the big changes.

gaearon · 2017-09-20T15:46:58Z

Regarding a jsfiddle demo - has that been a typical part of major release changelogs? I think the blog posts I linked to should cover that sort of detail for the big changes.

I don’t think we ever did this except for specific features we’re demoing in blog posts about features.

**what is the change?:** In response to helpful code review - - Add mention of dependency on `requestAnimationFrame` and need to polyfill that as well as `Map` and `Set` - Remove "New helpful warnings" section; it was incomplete, and there are so many new and updated warnings that it might not be reasonable to cover them in the changelog. **why make this change?:** Accuracy **test plan:** Visual inspection **issue:** issue facebook#8854

gaearon · 2017-09-20T19:08:13Z

CHANGELOG.md

+    Click to see more.
+  </summary>
+
+### JS Environment Requirements


Maybe worth changing to "New JS Environment Requirements" to better signal it is a change.

gaearon · 2017-09-20T19:09:46Z

CHANGELOG.md

+
+### JS Environment Requirements
+
+ * **React 16 depends on the collection types [Map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) and [Set](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set), as well as [requestAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame).** If you support older browsers and devices which may not yet provide these natively (eg <IE11), consider including a global polyfill in your bundled application, such as [core-js](https://github.com/zloirock/core-js) or [babel-polyfill](https://babeljs.io/docs/usage/polyfill/).


I would prefer we don't advertise core-js and babel-polyfill in this way without a specific example. I believe we had an example somewhere (in the issue?)

The trouble with this wording is it looks like we're promoting importing the whole polyfill (e.g. import 'babel-polyfill'). We should not. They are huge!

In the example we had, we specifically imported only the necessary ones.

(We don't have to literally paste an example here. It's enough to link to the docs, where we might want to add the same info anyway. Or we could link to a gist.)

Sounds good! Will fix.

gaearon · 2017-09-20T19:12:42Z

CHANGELOG.md

+  * When replacing `<A />` with `<B />`,  `B.componentWillMount` now always happens before  `A.componentWillUnmount`. Previously, `A.componentWillUnmount` could fire first in some cases.
+  * Previously, changing the ref to a component would always detach the ref before that component's render is called. Now, we change the ref later, when applying the changes to the DOM.
+  * It is not safe to re-render into a container that was modified by something other than React. This worked previously in some cases but was never supported. We now emit a warning in this case. Instead you should clean up your component trees using `ReactDOM.unmountComponentAtNode`. [See this example.](https://github.com/facebook/react/issues/10294#issuecomment-318820987)
+  * `componentDidUpdate` lifecycle no longer receives `prevContext` param. (See #8631)


This will not turn into a link in a Markdown file. GH only linkifies in comments and issues.

gaearon · 2017-09-20T19:13:16Z

CHANGELOG.md

+* ReactDOM.createPortal() is official and stable
+  ([@gaearon](https://github.com/gaearon) in
+  [10675](https://github.com/facebook/react/pull/10675))
+* Allow [passing some "unknown" attributes through to DOM components](https://facebook.github.io/react/blog/2017/09/08/dom-attributes-in-react-16.html) (@nhunzaker in https://github.com/facebook/react/pull/10385 , https://github.com/facebook/react/pull/10564 , https://github.com/facebook/react/pull/10495 and others)


This also looks pretty bad in Markdown file. These need to be turned into real links.

gaearon · 2017-09-20T19:13:36Z

CHANGELOG.md

+  * Shallow renderer no longer calls `componentDidUpdate()` because DOM refs are not available. This also makes it consistent with `componentDidMount()` (which does not get called in previous versions either).
+  * Shallow renderer does not implement `unstable_batchedUpdates()` anymore.
+- **The names and paths to the single-file browser builds have changed to emphasize the difference between development and production builds.** For example:
+  - react/dist/react.js → react/umd/react.development.js


We should put filenames in backticks for nicer formatting.

gaearon · 2017-09-20T19:16:23Z

CHANGELOG.md

+
+### Major Changes
+
+* **Improved error handling with introduction of "error boundaries".** [Error boundaries](https://facebook.github.io/react/blog/2017/07/26/error-handling-in-react-16.html) are React components that catch JavaScript errors anywhere in their child component tree, log those errors, and display a fallback UI instead of the component tree that crashed.


I would prefer if we separated error boundaries and portals into a separate "New Features" section. We could also add that components can now return arrays and strings into it, and that custom DOM attributes are now passed through (since it's technically one of top requested features).

Then the second section would be "Breaking Changes". It's fine to repeat the "unknown attributes" thing there since in addition to being a new feature, it's also a breaking change. But other new features (portals, arrays, error boundaries) are not.

Sweet! I was struggling to find the groupings within 'major changes' and I really like those two. Will fix.

gaearon

Let's separate new features from breaking changes, make sure we don't recommend importing the whole Babel polyfill, and fix up the formatting.

flarnie · 2017-09-21T20:43:06Z

I will also add a note about the changes to server side rendering - nearly forgot that. In the original issue:

The server renderer has been completely rewritten, and now offers a streaming mode (ReactDOMServer.renderToNodeStream() and ReactDOMServer.renderToStaticNodeStream()). Server rendering does not use markup validation anymore, and instead tries its best to attach to existing DOM, warning about inconsistencies. And there is no data-reactid anymore! This server renderer code is still very new, so it is likely to have issues. Please report them.
Hydrating a server rendered container now has an explicit API. Use ReactDOM.hydrate instead of ReactDOM.render if you're reviving server rendered HTML. Keep using ReactDOM.render if you're just doing client-side rendering.

flarnie · 2017-09-21T21:09:09Z

Going to push an update and then visual inspect the markdown on my branch. Will probably push a few improvements after that.

flarnie · 2017-09-21T21:54:23Z

gaearon

Left minor nits.

gaearon · 2017-09-21T22:15:28Z

CHANGELOG.md

+
+### New JS Environment Requirements
+
+ * **React 16 depends on the collection types [Map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) and [Set](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set), as well as [requestAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame).** If you support older browsers and devices which may not yet provide these natively (eg <IE11), [you may want to include a polyfill](https://gist.github.com/gaearon/9a4d54653ae9c50af6c54b4e0e56b583).


Tiny nit: eg => e.g.

gaearon · 2017-09-21T22:16:50Z

CHANGELOG.md

+
+### New Features
+* Components can now return arrays and strings from `render`. (Docs coming soon!)
+* **Improved error handling with introduction of "error boundaries".** [Error boundaries](https://facebook.github.io/react/blog/2017/07/26/error-handling-in-react-16.html) are React components that catch JavaScript errors anywhere in their child component tree, log those errors, and display a fallback UI instead of the component tree that crashed.


Why is this one bold alone? Let's either make all of them bold or none. They're roughly the same level of importance.

gaearon · 2017-09-21T22:18:58Z

CHANGELOG.md

+### New Features
+* Components can now return arrays and strings from `render`. (Docs coming soon!)
+* **Improved error handling with introduction of "error boundaries".** [Error boundaries](https://facebook.github.io/react/blog/2017/07/26/error-handling-in-react-16.html) are React components that catch JavaScript errors anywhere in their child component tree, log those errors, and display a fallback UI instead of the component tree that crashed.
+* `ReactDOM.createPortal()` is official and stable


It's not clear what it is. We generally try to make changelog easy to read for somehow who's not very deeply familiar with React. For example this could say: "First-class support for declaratively rendering a subtree into another DOM node with ReactDOM.createPortal()."

(I don't think it's important to give the PR number here since the only thing my PR did was rename a method. But people reading this probably aren't familiar with the whole idea itself. IMO it's only useful to link to PRs if they show actual implementation. For this case let's just not link to it.)

Yea - I was trying to find something to link to since we don't have docs yet but I can just say 'Docs coming soon' like in one of the previous points.

gaearon · 2017-09-21T22:22:38Z

CHANGELOG.md

+  ([@gaearon](https://github.com/gaearon) in
+  [#10675](https://github.com/facebook/react/pull/10675))
+* Streaming mode for server side rendering is enabled with `ReactDOMServer.renderToNodeStream()` and `ReactDOMServer.renderToStaticNodeStream()`. ([@aickin](https://github.com/aickin) in [#10425](https://github.com/facebook/react/pull/10425), [#10044](https://github.com/facebook/react/pull/10044), [#10039](https://github.com/facebook/react/pull/10039), [#10024](https://github.com/facebook/react/pull/10024), [#9264](https://github.com/facebook/react/pull/9264), and others.)
+* Allow [passing some "unknown" attributes through to DOM components](https://facebook.github.io/react/blog/2017/09/08/dom-attributes-in-react-16.html) ([@nhunzaker](https://github.com/nhunzaker) in [#10385](https://github.com/facebook/react/pull/10385), [10564](https://github.com/facebook/react/pull/10564), [#10495](https://github.com/facebook/react/pull/10495) and others)


This looks like a commit message. Let's rephrase to match other items? For example, "React DOM now allows passing non-standard attributes."

Agreed. I played around with getting "attribute whitelist" in there somewhere, but 👍 to this change.

gaearon · 2017-09-21T22:23:37Z

CHANGELOG.md

+  * `componentDidUpdate` lifecycle no longer receives `prevContext` param. ([@bvaughn](https://github.com/bvaughn) in [#8631](https://github.com/facebook/react/pull/8631))
+  * Shallow renderer no longer calls `componentDidUpdate()` because DOM refs are not available. This also makes it consistent with `componentDidMount()` (which does not get called in previous versions either).
+  * Shallow renderer does not implement `unstable_batchedUpdates()` anymore.
+- **The names and paths to the single-file browser builds have changed to emphasize the difference between development and production builds.** For example:


Nit: not clear why this one is bold but others aren't

nhunzaker · 2017-09-21T22:57:16Z

CHANGELOG.md

+    * To work around this, you can either use [the new portal API](https://github.com/facebook/react/issues/10309#issuecomment-318433235) or [refs](https://github.com/facebook/react/issues/10309#issuecomment-318434635).
+  * Minor changes to `setState` behavior:
+    * Calling `setState` with null no longer triggers an update. This allows you to decide in an updater function if you want to re-render.
+    * Calling `setState` directly in render always causes an update. This was not previously the case. Regardless, you should not be calling `setState` from render.


Off topic, but I wonder if it's possible to add a developer warning for this recommendation.

Seems like a good idea - not sure how easy it would be to add a warning for that, without doing something hacky like checking the caller.

nhunzaker

Thanks for compiling all of this! Looks good, but I agree with Dan's comments.

gaearon · 2017-09-22T15:06:43Z

CHANGELOG.md

+* The server renderer has been completely rewritten, with some improvements:
+  * Server rendering does not use markup validation anymore, and instead tries its best to attach to existing DOM, warning about inconsistencies. And there is no data-reactid anymore.
+  * Hydrating a server rendered container now has an explicit API. Use `ReactDOM.hydrate` instead of `ReactDOM.render` if you're reviving server rendered HTML. Keep using `ReactDOM.render` if you're just doing client-side rendering.
+* When "unknown" props are passed to DOM components, in some cases, React will now render them in the DOM. [See this post for more details.](https://facebook.github.io/react/blog/2017/09/08/dom-attributes-in-react-16.html) ([@nhunzaker](https://github.com/nhunzaker) in [#10385](https://github.com/facebook/react/pull/10385), [10564](https://github.com/facebook/react/pull/10564), [#10495](https://github.com/facebook/react/pull/10495) and others)


"in some cases" sounds pretty restrictive but in practice they will almost always be passed (except for invalid values). Let's change this to "for valid values" (and keep the link to the post).

Sounds good!

gaearon · 2017-09-22T15:08:52Z

CHANGELOG.md

+  - `react-dom/dist/react-dom.js` → `react-dom/umd/react-dom.development.js`
+  - `react-dom/dist/react-dom.min.js` → `react-dom/umd/react-dom.production.min.js`
+* The server renderer has been completely rewritten, with some improvements:
+  * Server rendering does not use markup validation anymore, and instead tries its best to attach to existing DOM, warning about inconsistencies. And there is no data-reactid anymore.


"And there is no data-reactid anymore" sounds a but odd to me. Maybe "It also doesn't use comments for empty components and data-reactid attributes on each node anymore."

gaearon · 2017-09-22T15:09:32Z

CHANGELOG.md

+  * Hydrating a server rendered container now has an explicit API. Use `ReactDOM.hydrate` instead of `ReactDOM.render` if you're reviving server rendered HTML. Keep using `ReactDOM.render` if you're just doing client-side rendering.
+* When "unknown" props are passed to DOM components, in some cases, React will now render them in the DOM. [See this post for more details.](https://facebook.github.io/react/blog/2017/09/08/dom-attributes-in-react-16.html) ([@nhunzaker](https://github.com/nhunzaker) in [#10385](https://github.com/facebook/react/pull/10385), [10564](https://github.com/facebook/react/pull/10564), [#10495](https://github.com/facebook/react/pull/10495) and others)
+
+### Removed deprecations


Capitalisation nit to match other sections: Removed Deprecations

gaearon · 2017-09-22T15:11:43Z

CHANGELOG.md

+  * Server rendering does not use markup validation anymore, and instead tries its best to attach to existing DOM, warning about inconsistencies. And there is no data-reactid anymore.
+  * Hydrating a server rendered container now has an explicit API. Use `ReactDOM.hydrate` instead of `ReactDOM.render` if you're reviving server rendered HTML. Keep using `ReactDOM.render` if you're just doing client-side rendering.
+* When "unknown" props are passed to DOM components, in some cases, React will now render them in the DOM. [See this post for more details.](https://facebook.github.io/react/blog/2017/09/08/dom-attributes-in-react-16.html) ([@nhunzaker](https://github.com/nhunzaker) in [#10385](https://github.com/facebook/react/pull/10385), [10564](https://github.com/facebook/react/pull/10564), [#10495](https://github.com/facebook/react/pull/10495) and others)
+


I think we should add a separate point about error boundaries here as it is a breaking change. Specifically:

Errors in the render and lifecycle methods now unmount the component tree by default. To prevent this, add error boundaries to the appropriate places in the UI. (And make it a link)

@gaearon

**what is the change?:** Thanks to the kind code review comments of @gaearon and @nhunzaker we have - removed the non-deterministic bold styling on some bullet points - improved wording of the bullet points for portals, attribute whitelist changes, and server rendering changes - Add note about error boundaries including a breaking change to error handling behavior. - punctuation and capitalization fixes **why make this change?:** Clarity and correctness **test plan:** Visual inspection **issue:** facebook#8854

@gaearon

* Update changelog for unreleased 16.0 changes (#10730) * First shot at updating changelog for 16.0 **what is the change?:** Added an 'unreleased' section to the changelog with info from #10294 **why make this change?:** To get things set for the 16.0 release. **test plan:** Visual inspection **issue:** #8854 * Fix typos and formatting errors in changelog * Add requestAnimationFrame and remove "New helpful warnings" **what is the change?:** In response to helpful code review - - Add mention of dependency on `requestAnimationFrame` and need to polyfill that as well as `Map` and `Set` - Remove "New helpful warnings" section; it was incomplete, and there are so many new and updated warnings that it might not be reasonable to cover them in the changelog. **why make this change?:** Accuracy **test plan:** Visual inspection **issue:** issue #8854 * Improve wording * Improve wording and fix missing links * Add backticks to file names & code; wording tweak * Break "Major Changes" into "New Feature" and "Breaking Changes" * Add server side render changes to 16.0 changelog * Change gist link from mine to gaearons * Add note about returning fragments * fix misc nits * Misc. formatting/wording fixes to changelog **what is the change?:** Thanks to the kind code review comments of @gaearon and @nhunzaker we have - removed the non-deterministic bold styling on some bullet points - improved wording of the bullet points for portals, attribute whitelist changes, and server rendering changes - Add note about error boundaries including a breaking change to error handling behavior. - punctuation and capitalization fixes **why make this change?:** Clarity and correctness **test plan:** Visual inspection **issue:** #8854 * fix broken link * Fixes #9667: Updated createTextInstance to create the text node on correct document (#10723) * Record sizes * Add a changelog for elements having the same key (#10811) * Add a changelog for elements having the same key * Reword * Markdown fixs on "DOM Attributes in React 16" post (#10816) * Include tag name into the table snapshot (#10818) * Update DOM warning wording and link (#10819) * Update DOM warning wording and link * Consistently use "Invalid" for known misspellings * Update license headers BSD+Patents -> MIT Did find and replace in TextMate. ``` find: (?:( \*)( ))?Copyright (?:$c$ )?(\d{4})\b.+Facebook[\s\S]+(?:this source tree|the same directory)\.$ replace: $1$2Copyright (c) $3-present, Facebook, Inc.\n$1\n$1$2This source code is licensed under the MIT license found in the\n$1$2LICENSE file in the root directory of this source tree. ``` * Change license and remove references to PATENTS Only remaining references: ``` docs/_posts/2014-10-28-react-v0.12.md 51:You can read the full text of the [LICENSE](https://github.com/facebook/react/blob/master/LICENSE) and [`PATENTS`](https://github.com/facebook/react/blob/master/PATENTS) files on GitHub. docs/_posts/2015-04-17-react-native-v0.4.md 20:* **Patent Grant**: Many of you had concerns and questions around the PATENTS file. We pushed [a new version of the grant](https://code.facebook.com/posts/1639473982937255/updating-our-open-source-patent-grant/). src/__mocks__/vendor/third_party/WebComponents.js 8: * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt ``` * Version bumps to use MIT license * Add ReactTestRenderer documentations (#10692) * Add ReactTestRenderer documentations * Add TestRenderer documentations * TestRenderer is not experiment * Add a link for jsdom * Use ES Modules syntax * Twaek * Add a Link component * Use Jest assertions * Move a documentation for createNodeMock to Idea section * Renamed * Tweak * Rename * More explicit * Add a usecase for createNodeMock * Add changelog for 15.6.2 * Add 15.6.2 blog post to master * Add Nate to authors on master * Bump object-assign patch range to match main package.json * Flow should ignore node_modules/create-react-class * Update error codes * Update CHANGELOG for React 16 * v16.0.0 * Doc updates for React 16 + blog post (#10824) * Doc updates for React 16 + blog post * Add link to Sophie's post * Fix React links on the website (#10837) * Fix React links on the website * Fix code editor * Fix code editor, attempt 2 * Doc change for prevContext removal in CDU (#10836) * Doc change for prevContext removal in CDU Ref: #8631 * Minor rewording * Fix note formatting * React.createPortal is not a function (#10843) * Update Portals Documentation (#10840) * Update Portals Documentation Correct some grammar to be more explicit and clear. Update example CodePen to better match code found in documentation. Update code example styles to match other code examples (ie. 'State and Lifecycle', 'Handling Events'). * Clean up comment to be accurate to example There was a small comment overlooked when reviewing the documentation. This fixes it to be accurate to the example as well as grammatically correct. * Update portals.md * More fixes * Update name of property initializer proposal (#10812) The proposal for property initializers is called [Public Class Fields](https://tc39.github.io/proposal-class-public-fields/) now (part of the combined [Class Fields](https://github.com/tc39/proposal-class-fields) proposal). * Fix portal link (#10845) * Update docs for React 16 (#10846) * Minor doc edit * Rename urls

flarnie added 2 commits September 18, 2017 14:37

First shot at updating changelog for 16.0

dcbbeae

**what is the change?:** Added an 'unreleased' section to the changelog with info from facebook#10294 **why make this change?:** To get things set for the 16.0 release. **test plan:** Visual inspection **issue:** facebook#8854

Fix typos and formatting errors in changelog

b623165

flarnie requested review from sophiebits and gaearon September 18, 2017 06:03

facebook-github-bot added the CLA Signed label Sep 18, 2017

flarnie mentioned this pull request Sep 18, 2017

Add 'Unreleased' section to changelog; update 'contributing' docs #9532

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gaearon reviewed Sep 18, 2017

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koba04 reviewed Sep 19, 2017

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flarnie added 2 commits September 20, 2017 10:14

Improve wording

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gaearon reviewed Sep 20, 2017

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gaearon requested changes Sep 20, 2017

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Improve wording and fix missing links

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flarnie added 2 commits September 21, 2017 13:45

Add backticks to file names & code; wording tweak

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Break "Major Changes" into "New Feature" and "Breaking Changes"

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flarnie added 4 commits September 21, 2017 14:09

Add server side render changes to 16.0 changelog

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Change gist link from mine to gaearons

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Add note about returning fragments

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fix misc nits

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gaearon approved these changes Sep 21, 2017

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flarnie added 2 commits September 22, 2017 14:34

fix broken link

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flarnie merged commit cdfbe6b into facebook:master Sep 22, 2017

NE-SmallTown mentioned this pull request Sep 24, 2017

Support React 16 ant-design/ant-design#5377

Closed

27 tasks

		- The deprecations introduced in 15.x have been removed from the core package. React.createClass is now available as create-react-class, React.PropTypes as prop-types, React.DOM as react-dom-factories, react-addons-test-utils as react-dom/test-utils, and shallow renderer as react-test-renderer/shallow. See [15.5.0](https://facebook.github.io/react/blog/2017/04/07/react-v15.5.0.html) and [15.6.0](https://facebook.github.io/react/blog/2017/06/13/react-v15.6.0.html) blog posts for instructions on migrating code and automated codemods.

		### New helpful warnings


		### JS Environment Requirements

		* React 16 depends on the collection types [Map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) and [Set](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set), as well as [requestAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame). If you support older browsers and devices which may not yet provide these natively (eg <IE11), consider including a global polyfill in your bundled application, such as [core-js](https://github.com/zloirock/core-js) or [babel-polyfill](https://babeljs.io/docs/usage/polyfill/).


		### Major Changes

		* Improved error handling with introduction of "error boundaries". [Error boundaries](https://facebook.github.io/react/blog/2017/07/26/error-handling-in-react-16.html) are React components that catch JavaScript errors anywhere in their child component tree, log those errors, and display a fallback UI instead of the component tree that crashed.


		### New JS Environment Requirements

		* React 16 depends on the collection types [Map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) and [Set](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set), as well as [requestAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame). If you support older browsers and devices which may not yet provide these natively (eg <IE11), [you may want to include a polyfill](https://gist.github.com/gaearon/9a4d54653ae9c50af6c54b4e0e56b583).

Update changelog for unreleased 16.0 changes #10730

Update changelog for unreleased 16.0 changes #10730

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flarnie commented Sep 21, 2017 • edited

flarnie commented Sep 21, 2017

flarnie commented Sep 21, 2017

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flarnie commented Sep 21, 2017 •

edited