What is the difference between render and return in React Js?

Whenever you work in React, you see render and return methods. However, many developers are not aware of the difference between the two. This article will help you understand when to use which method and when not to use it, along with the differences between these two methods with examples.

Let's get started.

What is the Render in ReactJS?

In ReactJS, "render" is a method specific to class components. It's like a set of instructions for showing what should be seen on the screen. When you call the render method, it gives back JSX elements that show how the component should look. These JSX elements are then turned into real HTML pieces and shown on the webpage. React handles calling the render method for us, and it's really important for making class components that can change what they show to users.

For example

Consider a weather app. If it's sunny, the render method might blueprint a sunny icon and temperature display; if it's rainy, it'll blueprint a rainy icon instead.

import React from "react";

class App extends React.Component {
    render() {
        const isSunny = true; // Assume determined by data
        const temperature = 25; // Assume fetched from API
        const weatherIcon = isSunny ? <img src="https://t3.ftcdn.net/jpg/02/50/08/68/360_F_250086872_srlXRqANYR2IbNfIylRDc3eMO9MinjnV.jpg" alt="Sunny" /> : <img src="https://atlas-content-cdn.pixelsquid.com/stock-images/weather-forecast-rain-7G5MZq7-600.jpg" alt="Rainy" />;

        return (
            <div>
                {weatherIcon}
                <p>Temperature: {temperature}°C</p>
            </div>
        );
    }
}

export default App

Inside the render method, we create UI elements using JSX syntax. In this example, we conditionally render a weather icon based on whether isSunny is true or false.

The render method allows for dynamic content generation. Here, the weatherIcon changes based on the value of isSunny.

The render method returns JSX elements enclosed within parentheses. These JSX elements represent the UI structure of the component.

The render method is part of the React component lifecycle. It gets invoked automatically whenever the component needs to update or re-render.

What is the Return in ReactJS?

In ReactJS, the return statement is crucial for functional components. It tells the component what to show on the screen. You can think of it as the last step where the component gives its final output to the user.

For example

Imagine a basic functional component named Button, showcasing a button element. Within this component's return statement, we specify the JSX code for the button element we want to display.

import React from "react";

const Button = () => {
    return (
        <button>
            Click Me
        </button>
    );
};

export default Button;

Here, the return statement inside the Button component returns a single button element with the text "Click Me".

The return statement in ReactJS returns a single JSX element or value from the component. However, you may include multiple components in the return statement using a fragment (<> </>). Simply enclose all of your elements within the fragment.

Difference Between the Return and Render Methods in React

In ReactJS, the return statement is important in functional components. It's how you say what should show up on the screen. Unlike in class components, where we use the render method, in functional components, the return statement is what we rely on to make things happen. It's a key part of how React works with functional programming.

Render Method:

Flexibility: Renders can incorporate logic beyond just returning JSX, such as conditional rendering, mapping through arrays, and more.

Dynamic Templating: Enables dynamic adjustments to the UI based on changing data or conditions.

Class Components Exclusive: Primarily associated with class components, which offer additional lifecycle methods beyond just rendering.

Return Method:

Functional Approach: Fits seamlessly within the functional programming instance, emphasizing pure functions and immutability.

Conciseness: Encourages a more streamlined and concise component structure, particularly with the rise of React hooks.

Functional Components: Intrinsic to functional components, which are simpler and more lightweight compared to class components.

Let's break down the differences between the render and return methods using the provided examples. Consider a simple React component that displays a greeting message based on the time of day.

Render Method:

import React from "react";

class Greeting extends React.Component {
    render() {
        const timeOfDay = new Date().getHours();
        let greetingMessage;

        if (timeOfDay < 12) {
            greetingMessage = "Good morning!";
        } else if (timeOfDay < 18) {
            greetingMessage = "Good afternoon!";
        } else {
            greetingMessage = "Good evening!";
        }

        return <div>{greetingMessage}</div>;
    }
}

export default Greeting;

Return Method:

import React from "react";

const Greeting = () => {
    const timeOfDay = new Date().getHours();
    let greetingMessage;

    if (timeOfDay < 12) {
        greetingMessage = "Good morning!";
    } else if (timeOfDay < 18) {
        greetingMessage = "Good afternoon!";
    } else {
        greetingMessage = "Good evening!";
    }

    return <div>{greetingMessage}</div>;
};

export default Greeting;

Let us now look at the differences between these two approaches.

Syntax: In the render method, components are built as class components, containing rendering logic within the render() function. In contrast, the return method built components as functional components, directly returning JSX from the function.

Component Type: The render method uses class components, which are traditional React components that can hold state and have lifecycle methods. The return method utilizes functional components, which are simpler and often preferred for their concise syntax and easier testing.

Creating Logic: Both methods achieve similar outcomes in generating UI based on the timeOfDay variable. However, in the render method, the rendering logic is contained within the render() method, whereas in the return method, it is located directly within the function body.

Here's a simplified table diagram that shows the differences between the return and render methods in React.

Feature	Return Method	Render Method
Component Type	Functional Component	Class Component
Syntax	`const Component = () => { return (...); };`	`class Component extends React.Component { render() { return (...); }; };`
Usage	Used in functional components	Used in class components
Rendering Logic	Directly returns JSX elements	Encapsulates rendering logic in the `render()` method
State and Lifecycle	Cannot hold state or use lifecycle methods directly	Can hold state and use lifecycle methods
Dynamic Rendering	Limited flexibility for dynamic rendering	Offers more flexibility for dynamic rendering
Readability	Often cleaner and more concise	May require more code for complex UIs

When to Use and Avoid the Render and Return Method in React?

You should use:

The render method in React is used in class components to define the UI elements based on the component's state and props.

The return statement is used in functional components to directly return JSX elements from the function body.

You should avoid:

The render method should not be used in ReactJS functional components. Functional components do not require the render method; instead, JSX elements are directly returned from the function body.

Avoid using the return method in React class components, as it is specific to functional components. Instead, in class components.

Which method should we use, and when?

Use the return method for functional components and the render method for class components.

When your component requires managing state or employing lifecycle methods like componentDidMount or componentDidUpdate, it's advisable to use a class component. It's worth noting that you can achieve similar functionality using a functional component. Functional components offer the flexibility of utilizing hooks such as useState and useEffect to handle state and lifecycle events more succinctly and with greater clarity.

Functional components with the return method are often more concise and easier to read, especially for simpler UI components, and class components with the render method may be necessary for more complex UI components that require state management and lifecycle methods.

More and more in the React community, people are preferring functional components with hooks over class components. Why? Well, they've got easier syntax, they're better at making things run smoothly, and they're simpler to keep up with and fix.

After weighing everything up, you might decide to go for a functional component. With hooks like useState and useEffect, functional components offer a smooth way to deal with state and what happens during the lifecycle of your app. That's why a lot of developers are all about them; they're simple, and they get the job done efficiently.

Conclusion

Understanding the difference between render and return methods is important to becoming a successful developer in ReactJS. We have explained everything to you so that you can further enhance your career in React. The render method is used in class components, and the return method is used in functional components.

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