Allow multi-characters delimtier at serialization.

papaparse.js

@@ -326,9 +326,10 @@
 				return;
 
 			if (typeof _config.delimiter === 'string'
-				&& _config.delimiter.length === 1
-				&& Papa.BAD_DELIMITERS.indexOf(_config.delimiter) === -1)
+                && !Papa.BAD_DELIMITERS.filter(function(value) { return _config.delimiter.includes(value); }).length)
 			{
+				// We have a string as config and it does not contains any
+				// of the invalid delimiters.
 				_delimiter = _config.delimiter;
 			}
 

tests/test-cases.js

@@ -1396,6 +1396,12 @@ var UNPARSE_TESTS = [
 		config: { delimiter: RECORD_SEP },
 		expected: 'a' + RECORD_SEP + 'b' + RECORD_SEP + 'c\r\nd' + RECORD_SEP + 'e' + RECORD_SEP + 'f'
 	},
+	{
+		description: "Custom delimiter (Multi-character)",
+		input: [['A', 'b', 'c'], ['d', 'e', 'f']],
+		config: { delimiter: ', ' },
+		expected: 'A, b, c\r\nd, e, f'
+	},
 	{
 		description: "Bad delimiter (\\n)",
 		notes: "Should default to comma",