isMounted behavior different with create-react-class

[mridgway]

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

Bug

What is the current behavior?

Calling this.isMounted() in componentWillUnmount in prior versions would return true. Now it returns false.

I believe this was untested behavior before, but the new tests that were added may check the wrong value: https://github.com/facebook/react/blob/master/src/isomorphic/classic/class/__tests__/create-react-class-integration-test.js#L417 Changing this line to test for true will exhibit the behavior.

The fix would be to defer setting the __isMounted flag to false until after all mixins and the componentWillUnmount method were called on the component.

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

15.5.x and anything using create-react-class is broken. Working correctly in 15.4.x with React.createClass.

[mridgway]

I fixed this locally by splitting the IsMountedMixin into two:

  var IsMountedPreMixin = {
    componentDidMount: function () {
      this.__isMounted = true;
    }
  };

  var IsMountedPostMixin = {
    componentWillUnmount: function () {
      this.__isMounted = false;
    }
  };

Then installing the Post after the spec has been mixed in:

    mixSpecIntoComponent(Constructor, IsMountedPreMixin);
    mixSpecIntoComponent(Constructor, spec);
    mixSpecIntoComponent(Constructor, IsMountedPostMixin);

For the life of me I can't find the right repo to PR this against though.

[gaearon]

This should be fixed with create-react-class@15.6.0-rc.0. Can you please verify?

[mridgway]

I don't see that version published yet.

[gaearon]

It's not set to latest (still an RC) but it exists:

https://unpkg.com/create-react-class@15.6.0-rc.0/

Will turn into 15.6.0 tomorrow.

[mridgway]

Ah indeed. It's probably our internal registry being slow. I'll try it out soon.

[mridgway]

Confirmed working correctly in create-react-class@15.6.0-rc.0.

[gaearon]

Great. Thanks for sending the fix!