Should I learn ES6 before learning ReactJS?

No, you don’t have to learn es2015/es6 to learn react. But you may find many resources or React ecosystem uses ES6 extensively. Let's see some of the frequently used ES6 features,

  1. Destructuring: To get props and use them in a component

    // in es 5
    var someData = this.props.someData;
    var dispatch = this.props.dispatch;
    // in es6
    const { someData, dispatch } = this.props;
  2. Spread operator: Helps in passing props down into a component

    // in es 5
    <SomeComponent someData={this.props.someData} dispatch={this.props.dispatch} />
    // in es6
    <SomeComponent {...this.props} />
  3. Arrow functions: Makes compact syntax

    // es 5
    var users = (user) {
    return <li>{}</li>;
    // es 6
    const users = => <li>{}</li>);

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