react - disable submit button (es6)

component.js

export default class UploadComponent extends React.Component {
  constructor() {
    super();
    this.state = {
      title: '',          // initial state for your input
      desc: '',
      image: ''
    }
  }
  handleChange(e) {
    name = e.target.name.match(/\[(.*?)\]/)[1];      // change state when input value changed
    this.setState({
      [name]: e.target.value                        // dynamic key name with []
    });
  }

  render() {
    const validForm = this.state.title && this.state.desc && this.state.image;     // changed when state has changed, empty string will return false in JS
    return (
      <div>
          <form action="/images" className="col s12" method="post" acceptCharset="UTF-8" encType='multipart/form-data'>
            <div className="row">
              <input type='hidden' name='authenticity_token' value={ this.props.csrfToken } />
              <div className="input-field col s12">
                <input placeholder="Title" name="image[title]" type="text" className="validate" value={ this.state.title } onChange={ this.handleChange.bind(this) } />     // call back on change
                <label htmlFor="first_name">Title</label>
              </div>
              <div className="input-field col s12">
                <input name="image[desc]" type="text" className="validate" value={ this.state.desc } onChange={ this.handleChange.bind(this) } />
                <label htmlFor="desc">Description</label>
              </div>
              <div className="file-field input-field col s12">
                <div className="btn">
                  <span>Choose a image</span>
                  <input type="file" name="image[image]" accept="image/*" value={ this.state.image } onChange={ this.handleChange.bind(this) } />
                </div>
                <div className="file-path-wrapper">
                  <input className="file-path validate" type="text" />
                </div>
              </div>
              <div className="col s12">
                <button type='submit' className='submit btn waves-effect waves-light' name="action" disabled={ !validForm }>Upload</button>     // button disabled based on the value of a const calculated by state
              </div>
            </div>
          </form>
      </div>
      );
  }
}