How to apply CSS to the webview in React native app?

In the previous tutorial, we learn how to create React native app from an already-existing website using webview.

When I created an app from a website, the major challenge I faced is to apply the CSS.

I wanted to style some of the UI components. But there is no direct way. After. doing a lot of research and trying different things, I finally cracked it.

The first question is, can we add CSS to the React-Native…

Yes, you can.

CSS styles to a WebView component in a React Native app can be applied using the injectedJavaScript prop along with the source prop.

Let’s take the same example from our previous tutorial and will add the necessary code.

import * as React from "react";
import { WebView } from "react-native-webview";

export default class App extends React.Component {
  render() {

    // newly added code
    const injectedJavaScript = `
      const style = document.createElement('style');
      style.innerHTML = 'body { background-color: red; }';
      document.head.appendChild(style);
    `;

    return (
      <WebView 
        source={{ uri: 'https://example.com/' }} 
        style={{ marginTop: 20 }}

        //newly added code
        injectedJavaScript={injectedJavaScript}
      />
    );
  }
}

Code Explanation

You can modify the code inside the injectedJavaScript variable to apply CSS to any other UI component like buttons, tables, headings, etc…

In the above example, we have changed the background color of the HTML body to red.

Instead of the body, you can also apply CSS using id or class object.

The code inside the injectedJavaScript prop is JavaScript String. The code inside the string gets executed after loading the webpage (react-native app here). Just like standard JavaScript, you can use any CSS or JavaScript to manipulate DOM objects.

Make sure, you are cognizant of the code you are injecting as part of injectedJavaScript. Adding wrong can expose your app to vulnerability.

Aniruddha Chaudhari

I am a Python enthusiast who loves Linux and Vim. I hold a Master of Computer Science degree from NIT Trichy and have 10 years of experience in the IT industry, focusing on the Software Development Lifecycle from Requirements Gathering, Design, Development to Deployment. I have worked at IBM, Ericsson, and NetApp, and I share my knowledge on CSEstack.org.