React - Uncontrolled Component (DOM State)

1 - About

An uncontrolled component is a component such as form where the state is handled by the DOM itself (not react)

The inverse is called a controlled component where the state is controlled by React

3 - Usage

if:

  • you need to write an very difficult event handler (for every way your data can change)
  • you are converting a preexisting codebase to React,
  • you are integrating a React application with a non-React library.

4 - Example

with a input where a ref is used to get form values from the DOM.


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

  handleSubmit(event) {
    console.log('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>
    );
  }
}

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


<div id="root"></div>

5 - Documentation / Reference


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