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,
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;
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} />
Arrow functions: Makes compact syntax
// es 5
var users = usersList.map(function (user) {
return <li>{user.name}</li>;
});
// es 6
const users = usersList.map((user) => <li>{user.name}</li>);