title: React TypeError this._test is not a function
body: <p>Since im new to JavaScript and React, i really have problems figuring out the right syntax. </p>
  
  <p>Here my problem:</p>
  
  <p><code>_handleDrop(files)</code> should call the function <code>_validateXML(txt)</code> but doesn't. I receive this error <code>Uncaught TypeError: this._validateXML is not a function</code> and can't figure out why.
  The callBack <code>_handleDrop(files)</code> works fine.</p>
  
  <p>When i try this kind of syntax <code>_validateXML:function(txt)</code> i immediately get a error while compiling. Is that because of ecmascript?</p>
  
  <pre><code>import React from 'react';
  import './UploadXML.scss';
  import Dropzone from 'react-dropzone';
  import xml2js from 'xml2js';
  
  export default class UploadXML extends React.Component {
  
    constructor() {
      super();
      this._validateXML = this._validateXML.bind(this);
    }
  
    _validateXML(txt) {
      console.log('Received files: ', txt);
    }
  
    _handleDrop(files) {
      if (files.length !== 1) {
        throw new Error("Please upload a single file");
      }
      var file = files[0];
  
      console.log('Received files: ', file);
  
      this._validateXML(file);
    }
  
    render() {
      return (
        &lt;div&gt;
              &lt;Dropzone onDrop={this._handleDrop} multiple={false}&gt;
                &lt;div&gt;Try dropping some files here, or click to select files to upload.&lt;/div&gt;
              &lt;/Dropzone&gt;
        &lt;/div&gt;
      );
    }
  }
  </code></pre>