title: React Native slice() function undefined error
body: <p>I want to update my listview row for that I am trying to slice listview datasource but its raising below error:</p>
  
  <blockquote>
    <p>this.state.dataSource.slice is not a function. (In
    'this.state.dataSource.slice()', 'this.state.dataSource.slice' is
    undefined)</p>
  </blockquote>
  
  <p>And here is my code:</p>
  
  <pre><code>let newArray = this.state.dataSource.slice();
  newArray[indexToUpdate] = {
    //Here I am updating my values.
  };
  this.setState({
    dataSource: this.state.dataSource.cloneWithRows(newArray),
  });
  </code></pre>
  
  <p>Let me know if there is any error in my code or something wrong I have done.</p>