[javascript] React component not re-rendering on state change

I have a React Class that's going to an API to get content. I've confirmed the data is coming back, but it's not re-rendering:

var DealsList = React.createClass({
  getInitialState: function() {
    return { deals: [] };
  },
  componentDidMount: function() {
    this.loadDealsFromServer();
  },
  loadDealsFromServer: function() {
    var newDeals = [];

    chrome.runtime.sendMessage({ action: "findDeals", personId: this.props.person.id }, function(deals) {
      newDeals = deals;
    });

    this.setState({ deals: newDeals });
  },
  render: function() {
    var dealNodes = this.state.deals.map(function(deal, index) {
      return (
        <Deal deal={deal} key={index} />
      );
    });
    return (
      <div className="deals">
        <table>
          <thead>
            <tr>
              <td>Name</td>
              <td>Amount</td>
              <td>Stage</td>
              <td>Probability</td>
              <td>Status</td>
              <td>Exp. Close</td>
            </tr>
          </thead>
          <tbody>
            {dealNodes}
          </tbody>
        </table>
      </div>
    );
  }
});

However, if I add a debugger like below, newDeals are populated, and then once I continue, i see the data:

  loadDealsFromServer: function() {
    var newDeals = [];

    chrome.runtime.sendMessage({ action: "findDeals", personId: this.props.person.id }, function(deals) {
      newDeals = deals;
    });
    debugger
    this.setState({ deals: newDeals });
  },

This is what's calling deals list:

var Gmail = React.createClass({
  render: function() {
    return (
      <div className="main">
        <div className="panel">
          <DealsList person={this.props.person} />
        </div>
      </div>
    );
  }
});

Another oh-so-easy mistake, which was the source of the problem for me: I’d written my own shouldComponentUpdate method, which didn’t check the new state change I’d added.

I was going through same issue in React-Native where API response & reject weren't updating states

apiCall().then(function(resp) { this.setState({data: resp}) // wasn't updating }

I solved the problem by changing function with the arrow function

apiCall().then((resp) => {
    this.setState({data: resp}) // rendering the view as expected
}

For me, it was a binding issue. Using arrow functions solved it because arrow function doesn't create its's own this, its always bounded to its outer context where it comes from

In my case, I was calling this.setState({}) correctly, but I my function wasn't bound to this, so it wasn't working. Adding .bind(this) to the function call or doing this.foo = this.foo.bind(this) in the constructor fixed it.

My issue was that I was using 'React.PureComponent' when I should have been using 'React.Component'.

After looking into many answers (most of them are correct for their scenarios) and none of them fix my problem I realized that my case is a bit different:

In my weird scenario my component was being rendered inside the state and therefore couldn't be updated. Below is a simple example:

constructor() {
    this.myMethod = this.myMethod.bind(this);
    this.changeTitle = this.changeTitle.bind(this);

    this.myMethod();
}

changeTitle() {
    this.setState({title: 'I will never get updated!!'});
}

myMethod() {
    this.setState({body: <div>{this.state.title}</div>});
}

render() {
    return <>
        {this.state.body}
        <Button onclick={() => this.changeTitle()}>Change Title!</Button>
    </>
}

After refactoring the code to not render the body from state it worked fine :)

I'd like to add to this the enormously simple, but oh so easily made mistake of writing:

this.state.something = 'changed';

... and then not understanding why it's not rendering and Googling and coming on this page, only to realize that you should have written:

this.setState({something: 'changed'});

React only triggers a re-render if you use setState to update the state.