Prevent direct mutation of this.state (react/no-direct-mutation-state)

[feross]

https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/no-direct-mutation-state.md

NEVER mutate this.state directly, as calling setState() afterwards may replace
the mutation you made. Treat this.state as if it were immutable.

The only place that's acceptable to assign this.state is in a ES6 class component constructor.

Rule Details

This rule is aimed to forbid the use of mutating this.state directly.

Examples of incorrect code for this rule:

var Hello = createReactClass({
  componentDidMount: function() {
    this.state.name = this.props.name.toUpperCase();
  },
  render: function() {
    return <div>Hello {this.state.name}</div>;
  }
});

class Hello extends React.Component {
  constructor(props) {
    super(props)

    // Assign at instance creation time, not on a callback
    doSomethingAsync(() => {
      this.state = 'bad';
    });
  }
}

Examples of correct code for this rule:

var Hello = createReactClass({
  componentDidMount: function() {
    this.setState({
      name: this.props.name.toUpperCase();
    });
  },
  render: function() {
    return <div>Hello {this.state.name}</div>;
  }
});

class Hello extends React.Component {
  constructor(props) {
    super(props)

    this.state = {
      foo: 'bar',
    }
  }
}

[ungoldman]

Hi, I just ran into this error while working on a non-react project.

Unfortunately this rule applies to anything mutating something that looks like this.state, even when it's not in a react context at all. In my case it's in a choo context, where mutating state is conversely the norm and expected, and there is no setState method.

What this means is this rule is unilaterally enforcing a react convention for all code that looks similar, even when it shouldn't apply at all. I'm pegging standard to 15 for now -- I don't want to have to write eslint-disable-rule in possibly hundreds of component files.

Hoping there's a reasonable compromise here -- alternately we can eject and modify standard eslint rules ourselves, but I'd prefer to remain on the good ship standard.