write_csv_line doesn't have to be a prototype

lib/csv_split.js

@@ -12,14 +12,6 @@ var Splitter = function(input_stream, output_dir, group_by) {
     this.group_sequence = null;
 };
 
-Splitter.prototype.write_csv_line = function(arr) {
-    //adding quotes
-    var quoted_arr = arr.map(function(item) {
-        return '\"' + item + '\"';
-    });
-    return quoted_arr.toString() + '\n';
-};
-
 
 Splitter.prototype.split = function() {
     var self = this;
@@ -37,12 +29,12 @@ Splitter.prototype.drain = function(data) {
     var name = data.name;
     var outfile = path.resolve(this.output_dir, name + ".csv");
     if (this.write_streams[name]) {
-        this.write_streams[name].write(this.write_csv_line(data.data));
+        this.write_streams[name].write(write_csv_line(data.data));
     } else {
         var ws = fs.createWriteStream(outfile);
         this.write_streams[name] = ws;
-        ws.write(this.write_csv_line(this.header));
-        ws.write(this.write_csv_line(data.data));
+        ws.write(write_csv_line(this.header));
+        ws.write(write_csv_line(data.data));
     }
 };
 
@@ -68,6 +60,14 @@ Splitter.prototype.run = function() {
         });
 };
 
+var write_csv_line = function(arr) {
+    //adding quotes
+    var quoted_arr = arr.map(function(item) {
+        return '\"' + item + '\"';
+    });
+    return quoted_arr.toString() + '\n';
+};
+
 var clean_name = function(file_name) {
     // file_name cannot have '/', '\' in it
     // convert them into underscore