In a React component you need to return your JSX. If this is a functional one it is simply like this:

function Component() {

    return <div>Some JSX</div>;

}

If it is a class component, your render method should return some JSX.

class Component extends React.Component {

    render() { return <div>Some JSX</div>; }

}

Your code has only one return and this is for your map. So, put your code inside a top return.

import React, { Component } from react;

import Person from ./Person/Person;



class Persons extends Component {

  render() {

    return (

      <div>

        {this.props.persons.map((person, index) => {

          return (

            <div>

              <Person

                click={() => this.props.clicked(index)}

                name={person.name}

                age={person.age}

                key={person.id}

                changed={event => this.props.changed(event, person.id)}

              />

            </div>

          );

        })}

      </div>

    );

  }

}



export default Persons;