ReactJS isElement() Method

React.js library is all about splitting the app into several components. Each Component has its own lifecycle. React provides us some in-built methods that we can override at particular stages in the life-cycle of the component.

In this article, we will know how to use isElement() method. The isElement() method returns true if an element is any react element.

Creating React Application And Installing Module:

• Step 1: Create a React application using the following command.

  
  
  

  npx create-react-app foldername

• Step 2: After creating your project folder i.e. foldername, move to it using the following command.

  cd foldername

Project Structure: It will look like the following.

Example 1: Now write down the following code in the App.js file. Here, App is our default component where we have written our code.

App.js

import React from 'react';
import { isElement } from 'react-dom/test-utils';

// Defining our App Component
const App = () => {

// Function to demonstrate isElement() method
function func() {
   var a = isElement(el);
   console.log("The Following is an element :", a);
}

const el = <div>
    <h1>element</h1>
</div>

// Returning our JSX code
return <>
    <div>
        <h1>GeeksforGeeks</h1>
        <button onClick={func}>Click Here !!</button>
    </div>;
</>;
}

// Exporting your Default App Component
export default App

Step to Run Application: Run the application using the following command from the root directory of the project:

npm start

Output: Now open your browser and go to http://localhost:3000/, you will see the following output:

Example 2: Now write down the following code in the App.js file. Here, App is our default component where we have written our code.

App.js

import React from 'react';
import { isElement } from 'react-dom/test-utils';

// Defining our App Component
const App = () => {

// Function to demonstrate isElement() method
function func(){
   var element = document.getElementById('id')
   var a = isElement(element);
   console.log("The Following is an element :", a);
}
// Returning our JSX code
return <>
    <div id='el'>
        <h1>GeeksforGeeks</h1>
        <button onClick={func}>Click Here !!</button>
    </div>
</>;
}

// Exporting your Default App Component
export default App

Step to Run Application: Run the application using the following command from the root directory of the project:

npm start

Output: Now open your browser and go to http://localhost:3000/, you will see the following output:

Reference: https://reactjs.org/docs/test-utils.html#iselement