title: joining an array nested in an object inside of an array using .join() not working
body: <p>I am taking in a file, parsing it, storing the info in an object and pushing that object to an array.One of the values of the object is a 'sequence': [] name value pair. Once I store a DNA sequence into the value of 'sequence' in my object I want to join all of the elements. However, I have tried doing this using .join() to no avail. Below is my code:</p>
  
  <pre><code>// Check for the various File API support.
  if (window.File &amp;&amp; window.FileReader &amp;&amp; window.FileList &amp;&amp; window.Blob) {
    // Great success! All the File APIs are supported.
  } else {
    alert('The File APIs are not fully supported in this browser.');
  }
  
  var objArray = [];
  var obj;
  
  function parse(event) {
  //Get the file from HTML input tag
  var file = event.target.files[0];
  
  if(file) {
  
      //Create a new file reader
      var reader = new FileReader();
      //When the file reader loads
      reader.onload = function(evt) {
          //Add the contents of file to variable contents
          var contentsByLine = evt.target.result.split('\n'); 
          //Alert user the file upload has succeeded
          console.log('File ' + file.name + ' was successfully loaded.');
  
          for(var i in contentsByLine){
              if(contentsByLine[i][0] == '&gt;'){
                  obj = {
                      id: contentsByLine[i],
                      sequence: [],
                      lead_trim: 0,
                      trail_trim: 0
                  };
                  objArray.push(obj);
              }else{
                  obj.sequence.push(contentsByLine[i]);
              }
             // console.log(objArray[i]['sequence']);
          }
          console.log(objArray)
  
          // Create the DataView.
          var dataView = new Slick.Data.DataView();
  
          // Pass it as a data provider to SlickGrid.
          var grid = new Slick.Grid("#table", dataView, columns, options);
  
          // Make the grid respond to DataView change events.
          dataView.onRowCountChanged.subscribe(function (e, args) {
            grid.updateRowCount();
            grid.render();
          });
  
          dataView.onRowsChanged.subscribe(function (e, args) {
            grid.invalidateRows(args.rows);
            grid.render();
          });
  
          var data = [];
  
          for (var i in objArray){
              objArray[i]['sequence'].join();
              data.push(objArray[i]);
          }
  
          dataView.setItems(data);
          dataView.getItems();
          //console.log(data);
      }
      reader.readAsText(file);
  } else {
      alert('Failed to upload file!');
  }
  
  }
  
  document.getElementById('fileItem').addEventListener('change', parse, false);
  </code></pre>