converts and array of objects into a csv string

arr2csv.js

function arr2csv(arr) {
  var cols = [];
  /* get a list of unique columns */
  _.each(arr, function(item) {
    cols = _.union(_.keys(item), cols);
  });
  var csvRows = [cols.join("\t")];

  for ( var i = 0; i < arr.length; i++ ) {
    var row = arr[i];
    var csvRow = [];
    for ( var colI = 0; colI < cols.length; colI++ ) {
      csvRow.push(_.has(row,cols[colI]) ? row[cols[colI]] : "");
    }
    csvRows.push(csvRow.join("\t"));
  }

  return csvRows.join("\n");
}