Difference between React controlled component and uncontrolled component

controlled component react
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I am new to react and while learning I come across this example of controlled component.

function App() {
  let [fName, setFName]=useState('');

  return (
    <div className="container">
      <h1>Hello {fName }</h1>
      <input name ='fname' value={fName} onChange={(e)=> setFName(e.target.value)} type="text" placeholder="What's your first name?" />

    </div>
  );
}

just adding value={fName} makes is controlled . I don't actually understand what does it mean by controlled component and uncontrolled. Can you explain it from beginner prospective.


An uncontrolled component means that you will let the component itself manage the value. It's own internal mechanism will keep track of it.

Now when you add the value property to the input component, you will start to "control" the component yourself. The value you put into that property, will be the value that will be displayed. You can literally control the value yourself, by just passing it in as is, or by changing the value before passing it in.

Controlled vs Uncontrolled Components in React, WTF is the difference? Alex Ritzcovan In a controlled component, form data is handled by a React component. The alternative is uncontrolled components, where form data is handled by the DOM itself. Let's take a look at� In a controlled component, form data is handled by a React component. The alternative is uncontrolled components, where form data is handled by the DOM itself. Let’s take a look at each.


React: Controlled VS Uncontrolled Components, React: Controlled VS Uncontrolled Components. Understanding the difference between controlled and uncontrolled React components. Controlled components let you work with them using React’s internal state, while uncontrolled components require you to use a lower level API to achieve the same results. Ideally, you’ll want to focus on the good old controlled components unless you need to do something weird with other libraries.


Controlled Components

These components have what is called a callback function that is triggered each time we enter something new in the form element.

Triggering the function will typically store or update what we type in the same React component that displays the form element that was used

Most widespread use it with forms

class NameForm extends React.Component {
  constructor(props) {
    super(props);
    this.state = {value: ''};

    this.handleChange = this.handleChange.bind(this);
    this.handleSubmit = this.handleSubmit.bind(this);
  }

  handleChange(event) {
    this.setState({value: event.target.value});
  }

  handleSubmit(event) {
    alert('A name was submitted: ' + this.state.value);
    event.preventDefault();
  }

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <label>
          Name:
          <input type="text" value={this.state.value} onChange={this.handleChange} />
        </label>
        <input type="submit" value="Submit" />
      </form>
    );
  }
}

Unontrolled Components

These components such as <input> typically maintain their own state and update it based on user input.

In other words, they will accept what we type and have the responsibility of remembering it, and in order to retrieve the values they remembered, you have to get it when you need it.

The latter usually happens during form submission. They can be classified under uncontrolled components.

class NameForm extends React.Component {
  constructor(props) {
    super(props);
    this.handleSubmit = this.handleSubmit.bind(this);
    this.input = React.createRef();
  }

  handleSubmit(event) {
    alert('A name was submitted: ' + this.input.current.value);
    event.preventDefault();
  }

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <label>
          Name:
          <input type="text" ref={this.input} />
        </label>
        <input type="submit" value="Submit" />
      </form>
    );
  }
}

What are React controlled components and uncontrolled , This relates to stateful DOM components (form elements) and the React docs explain the difference: A Controlled Component is one that takes� The difference between them is that components that their value is set/passed and have a callback are called controlled components (<input type="text" value="value" onChange= {handleChangeCallbackFn} />) vs. traditional HTML where an input element handle their own value and can be read via refs called uncontrolled components (<value type="text" />).


React Controlled Vs Uncontrolled Component, Difference table between controlled and uncontrolled component � 1. It does not maintain its internal state. It maintains its internal states. � 2. Here, data is� For developers that use React, controlled components should be what you use when handling form data in your applications. They create a single source of truth, enable in-place feedback, and make


Controlled and Uncontrolled components in React!, Ok, then what is the difference? Let's Start with the controlled component! The controlled component is a way that you can handle the form input� Controlled component. in the above example, we use the controlled component to handle the form input value using React Hooks and every time you will type a new character, handleInputChange is


Controlled and Uncontrolled Input Values in React, What you submit is what you get. class Form extends React.Component{ formHandler(event){ event.preventDefault(); const name = this.input. In a controlled component, form data is handled by a React component. The alternative is uncontrolled components, where form data is handled by the DOM itself. To write an uncontrolled component, instead of writing an event handler for every state update, you can use a ref to get form values from the DOM. For example, this code accepts a single name in an uncontrolled component: