How to disable button in React.js

Question

I have this component:

import React from \'react\';

export default class AddItem extends React.Component {

add() {
    this.props.onButtonClick(this.input.         


        

Answer 1

You shouldn't be setting the value of the input through refs.

Take a look at the documentation for controlled form components here - https://facebook.github.io/react/docs/forms.html#controlled-components

In a nutshell

<input value={this.state.value} onChange={(e) => this.setState({value: e.target.value})} />

Then you will be able to control the disabled state by using disabled={!this.state.value}

Answer 2

Using refs is not best practice because it reads the DOM directly, it's better to use React's state instead. Also, your button doesn't change because the component is not re-rendered and stays in its initial state.

You can use setState together with an onChange event listener to render the component again every time the input field changes:

// Input field listens to change, updates React's state and re-renders the component.
<input onChange={e => this.setState({ value: e.target.value })} value={this.state.value} />

// Button is disabled when input state is empty.
<button disabled={!this.state.value} />

Here's a working example:

class AddItem extends React.Component {
  constructor() {
    super();
    this.state = { value: '' };
    this.onChange = this.onChange.bind(this);
    this.add = this.add.bind(this);
  }

  add() {
    this.props.onButtonClick(this.state.value);
    this.setState({ value: '' });
  }

  onChange(e) {
    this.setState({ value: e.target.value });
  }

  render() {
    return (
      <div className="add-item">
        <input
          type="text"
          className="add-item__input"
          value={this.state.value}
          onChange={this.onChange}
          placeholder={this.props.placeholder}
        />
        <button
          disabled={!this.state.value}
          className="add-item__button"
          onClick={this.add}
        >
          Add
        </button>
      </div>
    );
  }
}

ReactDOM.render(
  <AddItem placeholder="Value" onButtonClick={v => console.log(v)} />,
  document.getElementById('View')
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id='View'></div>