How To Implement a Modal Component in React

Introduction #

Modals are separate windows within an application, most often as a dialog box. They are a common user interface pattern for providing information or requiring confirmation.
In this tutorial you will learn about how to implement a modal component in your React project. You’ll create a Dashboard component to manage state and a button to access the modal. You’ll also develop a Modal component to build a modal and a button to close. Your project will display and close a modal upon clicking a button.

Prerequisites #

To complete this tutorial, you will need:

A basic understanding of React before starting this tutorial. You can learn more about React by following the How to Code in React.js series.

Step 1 — Starting the Dashboard Component #

The dashboard is where you will display your modal. To begin your dashboard, import an instance of React and the Component object into your Dashboard.js file. Declare a Dashboard component and set your state:
Dashboard.js

import React, { Component } from "react";

class Dashboard extends Component {
  constructor() {
    super();
    this.state = {
      show: false
    };
    this.showModal = this.showModal.bind(this);
    this.hideModal = this.hideModal.bind(this);
  }

  showModal = () => {
    this.setState({ show: true });
  };

  hideModal = () => {
    this.setState({ show: false });
  };
}

export default Dashboard

Your state includes the property show with the value of false. This allows you to hide the modal until a user prompts it to open. The functions showModal() updates your state with the .setState() method to change the value of your show property to true when a user opens the modal. Likewise, the .setState() method in your hideModal() function will close the modal and change the value in your show property to false.

Note: Remember to bind your functions on the constructor() using the .bind() method.

Once you’ve applied your state and functions, your render() lifecycle method will handle displaying your modal within the return() statement:
Dashboard.js

import React, { Component } from "react";

class Dashboard extends Component {
  // ...
  render() {
    return (
      <main>
        <h1>React Modal</h1>
        <button type="button" onClick={this.showModal}>
          Open
        </button>
      </main>
    );
  }
}

export default Dashboard

The button accepts the React JSX attribute onClick to apply the .showModal() function and open your modal. You will export your Dashboard component to a higher-order App component connected to your root HTML file.

Step 2 — Building the Modal Component #

Create a new file, Modal.js and declare a stateless functional Modal component with three arguments, handleClose, show, and children. The argument show represents the show property on your state:
Modal.js

import './modal.css';

const Modal = ({ handleClose, show, children }) => {
  const showHideClassName = show ? "modal display-block" : "modal display-none";

  return (
    <div className={showHideClassName}>
      <section className="modal-main">
        {children}
        <button type="button" onClick={handleClose}>
          Close
        </button>
      </section>
    </div>
  );
};

Your return() statement passes the argument children, represented as props.children, is a reference to the functionality of opening and closing the modal. The modal also contains a button with a the React JSX onClick attribute that accepts the hideModal() method, here represented as the argument handleClose, passed as props into your Dashboard component.
The variable showHideClassName assigns its value a conditional to check if the value of the show property in your state is true. If so, the modal will appear. Else, the modal will hide. The properties display-block and display-none to show and hide the modal are handled through the modal.css file imported into your Modal component.
Start a new file, modal.css, and set the rules to style the size, color, and shape of your Modal:
modal.css

.modal {
  position: fixed;
  top: 0;
  left: 0;
  width:100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.6);
}

.modal-main {
  position:fixed;
  background: white;
  width: 80%;
  height: auto;
  top:50%;
  left:50%;
  transform: translate(-50%,-50%);
}

.display-block {
  display: block;
}

.display-none {
  display: none;
}

This will produce a centered modal with a white box outline and a shaded background. With your Modal component complete, let’s integrate your component into your Dashboard.

Step 3 — Incorporating the Modal Component #

To combine your Modal into your Dashboard, navigate to your Dashboard.js file and import your Modal component below your React insantiation:
Dashboard.js

import React, { Component } from "react";
import Modal from './Modal.js';

class Dashboard extends Component {
  // ...
  render() {
    return (
      <main>
        <h1>React Modal</h1>
        <Modal show={this.state.show} handleClose={this.hideModal}>
          <p>Modal</p>
        </Modal>
        <button type="button" onClick={this.showModal}>
          Open
        </button>
      </main>
    );
  }
}

export default Dashboard

In your return() statement, include your Modal component to display and hide the modal. The attributes show and handleClose are props from your Modal component to manage the logic of your state and the hideModal() function.
Your Dashboard and Modal components will now render on your browser:

Observe how your new Modal component now opens and close.

Conclusion #

In this tutorial, you learned how React can be used to implement modals by passing props and functionality from one component to another.
To view this project live, here is a CodePen demo of this project.