title: How to get input value of TextField from Material UI without using onChange event?
body: <p>I tried to use <code>this.refs.myField.getValue()</code> or <code>this.refs.myTextField.input.value</code>. But, they are depreciated.</p>
  
  <p>I don't want to use <code>onChange</code> inside <code>TextField</code>, I just convert the text when clicking button Convert</p>
  
  <pre><code>import React from 'react';
  import TextField from '@material-ui/core/TextField';
  import Button from '@material-ui/core/Button';
  
  class Test extends React.Component {
    constructor(props) {
      super(props);
  
      this.state = {
        text: '',
      };
    };
  
    handleConvertString = (event) =&gt; {
      let str = this.refs.myField.getValue();
      this.setState({
        text: str.replace(/[dog]/gi, ''),
      })
    };
    render() {
      return (
        &lt;div&gt;
          &lt;TextField
            ref="myField"
            fullWidth
          /&gt;
          &lt;Button variant="outlined" href="#outlined-buttons" onClick={this.handleConvertString}&gt;
            Convert
          &lt;/Button&gt;
          &lt;h1&gt;{this.state.text}&lt;/h1&gt;
        &lt;/div&gt;
      )
      }
  }
  
  export default Test;
  </code></pre>