testautosize.js

/*jshint esnext:true */
class TestAutosize extends React.Component  {
  constructor(props){
    super(props);

    this.state = {
      searchText: 'some example text'
    }

    this.autosize = this.autosize.bind(this);
    this.handleChange = this.handleChange.bind(this);

  }

  autosize() {
     console.log(this._input.scrollWidth)
     this._input.style.width = '0px';
     this._input.style.width =  `${this._input.scrollWidth+2}px`;
  }

  handleChange(e){
    this.setState({
      searchText: e.target.value,
    })
    this.autosize()
  }

  componentDidMount(){
    this.autosize();
  }

  render() {
    return (
      <div>
        <input onChange={this.handleChange}
               value={this.state.searchText}
               ref={ c => this._input = c}
        />
      </div>
      )
  }
}


ReactDOM.render(<TestAutosize/>, document.getElementById('app'));