Add ReactDOM.hydrate() as explicit SSR hydration API #10339
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gaearon
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Updated to add deprecation messages and expanded tests for both APIs while we support them. |
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| {'Hello ' + this.props.hello} | ||
| </body> | ||
| </html> | ||
| describe('with old implicit hydration API', () => { |
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I copy pasted these tests into two separate groups.
One still calls render() and, for cases where markup is reused, we verify that in Fiber mode we print a deprecation. We can delete this group of tests in 17.
Another calls hydrate() and we don’t expect deprecations there. The new version also removes non-Fiber branches since hydrate() only exists in Fiber.
| @@ -305,7 +305,6 @@ function createOpenTagMarkup( | |||
| if (isRootElement) { | |||
| ret += ' ' + DOMMarkupOperations.createMarkupForRoot(); | |||
| } | |||
| ret += ' ' + DOMMarkupOperations.createMarkupForID(''); | |||
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If we remove this then we break existing usage of ReactDOM.render and have no way of showing the warning, no?
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Isn't the data-reactroot attribute enough for detection?
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I think this changes the behavior if you try to ReactDOM.render into a non-container. But maybe that's fine?
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What is a non-container?
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A child of the container. The React root is the first child of the container. It also has children. You're not supported to render into those.
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| warning( | ||
| false, | ||
| 'hydrate(): Expected to hydrate from server-rendered markup, but the passed ' + | ||
| 'DOM container node was empty. React will create the DOM from scratch.', |
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IMO we should revert this warning since it's valid to have an empty container if your server rendered "", null, false or [] at the root. You'll get a warning about hydration being a non-match later anyway, if it's not. We can potentially special case the bulk error message in #10085 if the only diff was that the container was empty.
First attempt at #10189.
data-reactidfrom new SSR.data-reactrootas heuristic for hydration.ReactDOM.hydrate()API that never clears the existing content.ReactDOM.render()will now print a deprecation message when it tries to reuse markup.lowPriorityWarning.This means
ReactDOM.render()would still attempt to hydrate when there’s an element root, but might not work for new features (like top level strings or fragments).ReactDOM.hydrate()would always hydrate.I have switched the integration test to use the new hydration API when available, and this let me remove the special case for top level text nodes that I added in #10333.