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Polyfill for getSnapshotBeforeUpdate #1

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merged 9 commits into from
Mar 28, 2018
Merged

Polyfill for getSnapshotBeforeUpdate #1

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b0688e3
Proof of concept polyfill for getSnapshotBeforeUpdate
bvaughn Mar 22, 2018
ab7a7ab
Restore instance.props/instance.state in the event of an error in get…
bvaughn Mar 23, 2018
366211f
Updated README. Could still use more work.
bvaughn Mar 23, 2018
d1ac34c
Improved README
bvaughn Mar 23, 2018
ce78769
README tweaks
bvaughn Mar 26, 2018
a00cf2e
Tweaking error messages
bvaughn Mar 26, 2018
668cbdf
Fixed typo
bvaughn Mar 26, 2018
16aa7fe
Tweaked error message
bvaughn Mar 28, 2018
ff70f44
Changed getSnapshot test to more closely mimic real usage
bvaughn Mar 28, 2018
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12 changes: 10 additions & 2 deletions README.md
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Expand Up @@ -4,7 +4,7 @@

React version 17 will deprecate several of the class component API lifecycles: `componentWillMount`, `componentWillReceiveProps`, and `componentWillUpdate`. (Read the [Update on Async rendering blog post](https://deploy-preview-596--reactjs.netlify.com/blog/2018/03/15/update-on-async-rendering.html) to learn more about why.) A couple of new lifecycles are also being added to better support [async rendering mode](https://reactjs.org/blog/2018/03/01/sneak-peek-beyond-react-16.html).

Typically, this type of change would require third party libraries to release a new major version in order to adhere to semver. However, the `react-lifecycles-compat` polyfill offers a way to use the new lifecycles with older versions of React as well (0.14.9+) so no breaking release is required!
Typically, this type of change would require third party libraries to release a new major version in order to adhere to semver. However, the `react-lifecycles-compat` polyfill offers a way to use the new lifecycles with older versions of React as well (0.14.9+) so no breaking release is required. This enables shared libraries to support both older and newer versions of React simultaneously.

## How can I use the polyfill

Expand Down Expand Up @@ -36,4 +36,12 @@ export default ExampleComponent;

## Which lifecycles are supported?

Currently, this polyfill supports [static `getDerivedStateFromProps`](https://deploy-preview-587--reactjs.netlify.com/docs/react-component.html#static-getderivedstatefromprops) and [`getSnapshotBeforeUpdate`](https://deploy-preview-587--reactjs.netlify.com/docs/react-component.html#getsnapshotbeforeupdate)- both introduced in version 16.3.
Currently, this polyfill supports [static `getDerivedStateFromProps`](https://deploy-preview-587--reactjs.netlify.com/docs/react-component.html#static-getderivedstatefromprops) and [`getSnapshotBeforeUpdate`](https://deploy-preview-587--reactjs.netlify.com/docs/react-component.html#getsnapshotbeforeupdate)- both introduced in version 16.3.

## Validation

Note that in order for the polyfill to work, none of the following lifecycles can be defined by your component: `componentWillMount`, `componentWillReceiveProps`, or `componentWillUpdate`.

Note also that if your component contains `getSnapshotBeforeUpdate`, `componentWillUpdate` must be defined as well.
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Did you mean componentDidUpdate?

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In other words I'd expect the person trying to use getSnapshotBeforeUpdate to want to migrate away from componentWillUpdate, not use it.

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Yes 😦 This was a typo.


An error will be thrown if any of the above conditions are not met.