title: Can't clear input field after pressing button
body: <pre><code>class CategoryBox extends Component {
    constructor(props) {
      super(props);
      this.state = {
        newCategoryTitle: '',
        errorMsg: null,
        updateCategoryTitle: '',
      };
      this.handleCreateCategory = this.handleCreateCategory.bind(this);
      this.handleUpdateCategory = this.handleUpdateCategory.bind(this);
    }
    ...
    ...
    handleUpdateCategory(e) {
      e.preventDefault();
      this.setState({
        updateCategoryTitle: ''
      });
    }
    render() {
      return (
      //...
      &lt;form&gt;
        &lt;input
          type={'text'}
          className={styles.tabSmallField}
          placeholder={ category.name }
          onChange={(e) =&gt; { this.setState({ updateCategoryTitle: e.target.value }); }} /&gt;
        &lt;button type="submit" onClick={this.handleUpdateCategory}&gt;Update&lt;/button&gt;
      &lt;/form&gt;
      //...
    }
  }
  </code></pre>
  
  <p>I want to clear input text field after pressing the button.</p>
  
  <p>It looks like it enters into "handleUpdateCategory(e)" after pressing the button. But it does not clear the input field above the button.</p>
  
  <p>How can I clear the input text field?</p>