React: “this” is undefined inside a component function

Question

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

    this.state = {
      loopActive: false,
      shuffleActive: false,
    }         


        

Answer 1

If you call your created method in the lifecycle methods like componentDidMount... then you can only use the this.onToggleLoop = this.onToogleLoop.bind(this) and the fat arrow function onToggleLoop = (event) => {...}.

The normal approach of the declaration of a function in the constructor wont work because the lifecycle methods are called earlier.