Class fields from properties in ReactJS

Question

I am having trouble figuring out how to correctly create a class field based on a property.

class Example extends Component {
  example_titles = props.titles;

  // ...
}

which results in

Line 7:  'props' is not defined  no-undef

I call this class in another file that works 100% correctly unless I add this tag with the following call <Example titles={["titles"]} />

I am using the stage 2 in Babel to eliminate constructors. I am aware of how to do this with constructors, but am struggling to understand this without them.

Answer 1

You can access the props in class properties with this.props.

class Example extends React.Component {
  example_titles = this.props.titles;

  render() {
    return (
      <div>
        {this.example_titles.map((title, index) => (
          <div key={index}>{title}</div>
        ))}
      </div>
    );
  }
}

ReactDOM.render(
  <Example titles={["titles"]} />,
  document.getElementById("root")
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>

<div id="root"></div>