React virtual DOM creation

React is a popular JavaScript library used for building user interfaces. It improves performance and rendering speed by using virtual DOM. This article will introduce in detail the creation method, usage and cases of React's virtual DOM, as well as related code and explanations.

What is virtual DOM?

Virtual DOM is an important concept in React. It is a lightweight JavaScript object used to describe the hierarchical structure of the real DOM. Virtual DOM can operate in memory without directly manipulating the DOM, thus improving performance and rendering speed.

How to create virtual DOM

React's virtual DOM is created through JSX syntax. JSX is an HTML-like syntax that can be used in JavaScript. It allows us to mix HTML markup and JavaScript code together, making it easier to create UI components.

Here is a simple example showing how to create a virtual DOM using JSX:

const element = <h1>Hello, world!</h1>;

In this example, we create an <h1>element using JSX syntax and assign it to a variable element. This is actually a JavaScript object that describes the hierarchy and properties of this element.

Usage of virtual DOM

Once we create a virtual DOM, we can render it into the real DOM. React provides a ReactDOM.render()method for rendering virtual DOM into a specified DOM element.

Here is a simple example showing how to use ReactDOM.render()methods to render virtual DOM onto the page:

const element = <h1>Hello, world!</h1>;
ReactDOM.render(element, document.getElementById('root'));

In this example, we render the virtual DOM elementinto elements on the page <div id="root"></div>.

The case of virtual DOM

Here's a more complex example showing how to use virtual DOM to create a component with multiple child elements and attributes:

function App() {
    
    
  return (
    <div className="app">
      <h1>Hello, world!</h1>
      <p>This is a React app.</p>
    </div>
  );
}

ReactDOM.render(<App />, document.getElementById('root'));

In this example, we define a Appcomponent called , which contains an <div>element and two child <h1>elements <p>. We also <div>added a classNameproperty to the element for setting CSS styles.

Finally, we use ReactDOM.render()the method to <App>render the component onto the page.

Summarize

Virtual DOM is an important concept in React that can improve performance and rendering speed. We can create a virtual DOM using JSX syntax and ReactDOM.render()render it onto the page using methods. In actual development, virtual DOM can help us create complex UI components more easily while maintaining good performance and maintainability.