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create-subscription: call getValue in the constructor is too early

See original GitHub issue

Do you want to request a feature or report a bug?

BUG

What is the current behavior?

https://codepen.io/intptr/pen/djEzbr?editors=1010

I made an example to show the execution order of some lifecycle functions while remounting a component:

newComponent.constructor() -> oldComponent.componentWillUnmount() -> newComponent.componentDidMount()

create-subscription calls getValue in constructor and save the result to its state. Before componentDidMount called, any changes will be ignored.

If I remount a component wrapped by create-subscription component, and do something in its componentWillMount which will modify the source value, I will get the wrong value in componentDidMount in the new component.

newComp.constructor -> oldComp.cWU -> newComp.cDM
state = A              A -> B         A !! (correct: B)

What is the expected behavior?

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?

16.4.2 (latest)

Issue Analytics

State:
Created 5 years ago
Comments:16 (7 by maintainers)

Top GitHub Comments

1reaction

gaearoncommented, Aug 16, 2018

👍 Thanks for the repro cases, they’ve been helpful for the discussion!

1reaction

lixiaoyancommented, Aug 16, 2018

@gaearon I tried to make a runnable example yesterday and I found there’s no umd version of create-subscription on npm and then I gave it up 😂 I will take a look into CodeSandbox and try to make an online example later.

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