Don't recreate instance when resuming a class component's initial mount #9608
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sebmarkbage
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| newInstance.props = newProps; | ||
| newInstance.state = newState = newInstance.state || null; | ||
| newInstance.context = newContext; | ||
| // componentWillMount may have called setState. Process the update queue. |
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This comment is in the wrong place. Do you mean componentWillReceiveProps? If so, shouldn't this be gated on the existence of a componentWillReceiveProps?
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| @@ -444,6 +496,9 @@ module.exports = function( | |||
| if (typeof instance.componentDidMount === 'function') { | |||
| workInProgress.effectTag |= Update; | |||
| } | |||
|
|
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| instance.state = newState; | |||
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If I do componentWillMount() { this.state = {}; } What should it do?
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Recreating the class instance causes refs (and other callbacks) to close over stale instances. Instead, re-use the previous instance. componentWillMount is called again. We also call componentWillReceiveProps, to ensure that state derived from props remains in sync.
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**what is the change?:** A test was added for a change to Fiber's behavior in facebook#9608, and because of a bug in our CirclCI script it landed when failing for non-fiber runs of the tests. This just wraps the test in a feature flag because it seems clear it was only intended to test the new fiber behavior. Thanks to @gaearon for pairing on this! :) **why make this change?:** So that tests are passing on master. **test plan:** `npm run test ReactCompositeComponentState` **issue:** None - figured it out before anyone opened an issue afaik.
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**what is the change?:** A test was added for a change to Fiber's behavior in facebook#9608, and because of a bug in our CirclCI script it landed when failing for non-fiber runs of the tests. This just wraps the test in a feature flag because it seems clear it was only intended to test the new fiber behavior. Thanks to @gaearon for pairing on this! :) **why make this change?:** So that tests are passing on master. **test plan:** `npm run test ReactCompositeComponentState` **issue:** None - figured it out before anyone opened an issue afaik.
flarnie
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**what is the change?:** A test was added for a change to Fiber's behavior in #9608, and because of a bug in our CirclCI script it landed when failing for non-fiber runs of the tests. This just wraps the test in a feature flag because it seems clear it was only intended to test the new fiber behavior. Thanks to @gaearon for pairing on this! :) **why make this change?:** So that tests are passing on master. **test plan:** `npm run test ReactCompositeComponentState` **issue:** None - figured it out before anyone opened an issue afaik.
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Recreating the class instance causes refs (and other callbacks) to close over stale instances.
Instead, re-use the previous instance. componentWillMount is called again. We also call componentWillReceiveProps, to ensure that state derived from props remains in sync.