Call a React component inside a function, when a button is clicked

Question

The Container component is not getting rendered. Can anyone guide me why I'm not able to render the Container component?

App.js

import React, { Component } from "react";
import "./App.css";
import Container from "./Container";

class App extends Component {
  add() {
    return <Container />;
  }
  render() {
    return (
      <div className="App">
        <button onClick={() => this.add()}>CLICK</button>
      </div>
    );
  }
}

export default App;

Container.js

import React, { Component } from "react";

export default class Container extends Component {
 render() {
   return <h1>hello</h1>;
  }
}

Answer 1

You can set a state and render the component on button click

import React, { Component } from "react";
 import "./App.css";
 import Container from "./Container";

 class App extends Component {
  state = {
     addContainer: []
  }
  add() {
     this.setState(prevState => {addContainer: prevstate.addContainer.concat([0])})
  }
 render() {
  return (
   <div className="App">
     {this.state.addContainer.map(() => {
         return <Container />
     })}
     <button onClick={() => this.add()}>CLICK</button>
   </div>
  );
 }
}

export default App;

or if its just a single container whose visibility you want to toggle on button click

 import React, { Component } from "react";
 import "./App.css";
 import Container from "./Container";

 class App extends Component {
  state = {
     addContainer: false
  }
  add() {
     this.setState(prevState => {addContainer: !prevstate.addContainer)})
  }
 render() {
  return (
   <div className="App">
     {this.state.addContainer &&  <Container />}
     <button onClick={() => this.add()}>CLICK</button>
   </div>
  );
 }
}

export default App;

Answer 2

Your function isn't rendering because the return of your method add() isn't inside your render() method. It's inside the onClick(), so it won't render. Try like the snippet bellow:

class Container extends React.Component {
    render(){
      return <h1> Hello World </h1>
    }
}

class App extends React.Component {
  state= { render: false }
  add = () => {
    this.setState({render : !this.state.render})
  }
 render() {
  return (
   <div className="App">
     <button onClick={() => this.add()}>CLICK</button>
     { this.state.render &&
        <Container/>
     }
   </div>
  );
 }
}

ReactDOM.render(<App/>,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>

You can even toggle the <Container> rendering, as I did above, but you can't return a Component inside a onClick and expect that it'll be rendered.