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REFERENCEreact

react Documentation

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Controlled vs Uncontrolled

AI & DATA SCIENCE // controlled-vs-uncontrolled

The React Controlled vs Uncontrolled concept.

Syntax

// Syntax for Controlled vs Uncontrolled
const example = true;

Deep Dive Course

Detailed overview of the Controlled vs Uncontrolled React concept.

1Understanding Controlled vs Uncontrolled

Welcome to this deep dive into Controlled vs Uncontrolled.

When building interactive web applications, React is a powerful tool. The Controlled vs Uncontrolled concept is a foundational piece of the library. Let's explore its syntax and behavior in modern React.

### Legacy Content

A controlled form in React is one whose value is managed through React's state. In contrast, an uncontrolled form manages its own state through references (ref).

## Controlled Form:

In a controlled form, each input has a value managed by React through state.

import React, { useState } from "react";

      function ControlledForm() {
        const [name, setName] = useState("");

        const handleChange = (event) => {
          setName(event.target.value);
        };

        return (
          
            
            Submit
          
        );
      }

      export default ControlledForm;

## Uncontrolled Form:

In an uncontrolled form, references (ref) are used to directly access the values of form fields.

import React, { useRef } from "react";

      function UncontrolledForm() {
        const nameRef = useRef(null);

        const handleSubmit = (event) => {
          event.preventDefault();
          alert("Name entered: " + nameRef.current.value);
        };

        return (
          
            
            Submit
          
        );
      }

      export default UncontrolledForm;
📌

React updates the UI efficiently using a virtual DOM.

editor.html
// Example of Controlled vs Uncontrolled
console.log("Hello, React!");
localhost:3000

2Example: Basic Usage

Now let's examine a practical implementation. In the following example, we demonstrate how to apply Controlled vs Uncontrolled effectively.

Pay close attention to the syntax and the resulting output. By writing clean and modular React, we ensure that the codebase remains maintainable and bug-free.

💡

Notice how clean the syntax is.

editor.html
// Basic example for Controlled vs Uncontrolled
function Example() {
  return <div>Learning Controlled vs Uncontrolled</div>;
}
localhost:3000

3Example: Advanced Scenarios

Now let's examine a practical implementation. In the following example, we demonstrate how to apply Controlled vs Uncontrolled effectively.

Pay close attention to the syntax and the resulting output. By writing clean and modular React, we ensure that the codebase remains maintainable and bug-free.

editor.html
// Advanced example for Controlled vs Uncontrolled
function Advanced() {
  const data = useData('controlled-vs-uncontrolled');
  return <ErrorBoundary><View data={data} /></ErrorBoundary>;
}
localhost:3000

4Best Practices

To achieve true mastery over Controlled vs Uncontrolled, follow community best practices.

  • Keep your components pure whenever possible.
  • Always be aware of React's render cycle.

By following these guidelines, you make your code production-ready.

⚠️

Avoid unnecessary re-renders by using memoization tools when appropriate.

editor.html
// Best practices applied
const optimized = true;
localhost:3000

Examples

Example 01Basic Usage
// Basic example for Controlled vs Uncontrolled
function Example() {
  return <div>Learning Controlled vs Uncontrolled</div>;
}
Example 02Advanced Scenarios
// Advanced example for Controlled vs Uncontrolled
function Advanced() {
  const data = useData('controlled-vs-uncontrolled');
  return <ErrorBoundary><View data={data} /></ErrorBoundary>;
}

Best Practices

  • Keep your components pure whenever possible.
  • Always be aware of React's render cycle.

Frequently Asked Questions

When should I use Controlled vs Uncontrolled?

You should use Controlled vs Uncontrolled whenever your component logic requires its specific behavior to solve a problem.

Is Controlled vs Uncontrolled supported in React Native?

Most core React concepts apply to React Native as well, though the rendering elements differ.