Rendering elements and components is an important part of building applications with React. In this article, we will explore the different ways to render elements and components in React and how to choose the best option for your needs.
Rendering Elements
In React, an element is a plain object that represents a DOM element. Elements are the smallest building blocks of a React application, and they are created using the React.createElement()
function.
For example, consider the following element that represents a div
element:
const element =
React.createElement('div', {}, 'Hello, world!');
In this example, the React.createElement()
function creates a new element based on the tag name, props, and children that are passed to it. The first argument is the tag name, the second argument is the props object, and the third argument is the children of the element.
To render an element to the DOM, you need to pass it to the ReactDOM.render()
function. The ReactDOM.render()
function takes the element as an argument and renders it to the specified DOM node.
For example, consider the following code that renders the element
to the root
DOM node:
ReactDOM.render(element,
document.getElementById('root'));
In this example, the element
is rendered to the root
DOM node, and it will be displayed as a div
element with the text “Hello, world!” inside.
Rendering elements is a simple and efficient way to update the UI of a React application, but it has some limitations. Elements are static and cannot be modified once they are created, so they are not suitable for dynamic and interactive UI.
Rendering Components
To create dynamic and interactive UI in React, you need to use components. A component is a reusable and modular piece of code that represents a part of the UI. Components can be either functional or class-based, and they are created using the React.createElement()
function or the React.Component
class.
For example, consider the following functional component that represents a Button
:
import React from 'react';
function Button(props) {
return (
<button onClick={props.onClick}>
{props.label}
</button>
);
}
In this example, the Button
component is a functional component that returns a button
element with an onClick
prop and a label
prop. The onClick
prop is a callback function that is called when the button is clicked, and the label
prop is the text that is displayed on the button.
To render a component to the DOM, you need to pass it to the ReactDOM.render()
function just like you would with an element. The component will be rendered to the specified DOM node and will be updated whenever the component’s state or props change.
For example, consider the following code that renders the Button
component to the root
DOM node:
ReactDOM.render(<Button label="Click me"
onClick={() => alert('Hello, world!')} />,
document.getElementById('root'));
In this example, the Button
component is rendered to the root
DOM node, and it will be displayed as a button with the text “Click me”. When the button is clicked, an alert with the text “Hello, world!” will be displayed.
Rendering components is a powerful and flexible way to create dynamic and interactive UI in React, and it is the most commonly used way to build applications with the framework.
Choosing Between Elements and Components
When building applications with React, you need to decide whether to use elements or components to render your UI. Elements are simple and efficient, but they are static and cannot be modified once they are created. Components are more powerful and flexible, but they are more complex and require more setup.
As a general rule, you should use elements for simple and static UI, and you should use components for dynamic and interactive UI. For example, you might use elements for displaying simple text or images, and you might use components for displaying forms or interacting with APIs.
Conclusion
By understanding the strengths and limitations of elements and components, you can choose the best option for your needs and build scalable and maintainable applications with React.
Exercises
To review these concepts, we will go through a series of exercises designed to test your understanding and apply what you have learned.
What is an element in React?
An element in React is a plain object that represents a DOM element. Elements are created using the React.createElement()
function and are the smallest building blocks of a React application.
What is a component in React?
A component in React is a reusable and modular piece of code that represents a part of the UI. Components can be either functional or class-based, and they are created using the React.createElement()
function or the React.Component
class.
How do you render an element to the DOM in React?
To render an element to the DOM in React, you need to pass it to the ReactDOM.render()
function. The ReactDOM.render()
function takes the element as an argument and renders it to the specified DOM node.
How do you render a component to the DOM in React?
To render a component to the DOM in React, you need to pass it to the ReactDOM.render()
function just like you would with an element. The component will be rendered to the specified DOM node and will be updated whenever the component’s state or props change.
When should you use elements and when should you use components in React?
You should use elements for simple and static UI, and you should use components for dynamic and interactive UI. For example, you might use elements for displaying simple text or images, and you might use components for displaying forms or interacting with APIs.