diff --git a/JsFormat.sublime-settings b/JsFormat.sublime-settings
index 9c9f091..303ce0a 100644
--- a/JsFormat.sublime-settings
+++ b/JsFormat.sublime-settings
@@ -13,5 +13,8 @@
 	"break_chained_methods": false,
 
 	// jsformat options
-	"format_on_save": false
+	"format_on_save": false,
+	"format_by_extension_syntax": "both",
+	"format_file_extension": ["js", "json"],
+	"format_file_syntax": ["javascript", "json"]
 }
\ No newline at end of file
diff --git a/README.md b/README.md
index 89b1b7f..90f3d35 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,9 @@ In addition, the following settings are available in JsFormat/JsFormat.sublime-s
 * "unescape_strings": false,
 * "break_chained_methods": false*
 * "format_on_save": false
+* "format_by_extension_syntax": "both"  (both, extension, syntax)
+* "format_file_extension": ["js", "json"]
+* "format_file_syntax": ["javascript", "json"]
 
 I had temporary lapse of judgement a while back and merged a pull request that modified jsbeautifier. As a result, the functionality that
 was added from that pull request has been lost; ```"ensure_space_before_linestarters"``` is no longer supported.
diff --git a/js_formatter.py b/js_formatter.py
index dea9acf..d1f8924 100644
--- a/js_formatter.py
+++ b/js_formatter.py
@@ -50,13 +50,23 @@ def is_js_buffer(view):
 	syntaxPath = vSettings.get('syntax')
 	syntax = ""
 	ext = ""
-
-	if (fName != None): # file exists, pull syntax type from extension
-		ext = os.path.splitext(fName)[1][1:]
-	if(syntaxPath != None):
-		syntax = os.path.splitext(syntaxPath)[0].split('/')[-1].lower()
-
-	return ext in ['js', 'json'] or "javascript" in syntax or "json" in syntax
+	syntaxOrExtension = s.get("format_by_extension_syntax")
+	syntaxList = s.get("format_file_syntax")
+	extensionList = s.get("format_file_extension")
+	result = False
+
+	if (syntaxOrExtension in ['both', 'extension']):
+		if (fName != None): # file exists, pull syntax type from extension
+			ext = os.path.splitext(fName)[1][1:]
+			if (ext in extensionList):
+				result = True
+	if (syntaxOrExtension in ['both', 'syntax']):
+		if(syntaxPath != None):
+			syntax = os.path.splitext(syntaxPath)[0].split('/')[-1].lower()
+			if (syntax in syntaxList):
+				result = True;
+
+	return result
 
 class PreSaveFormatListner(sublime_plugin.EventListener):
 	"""Event listener to run JsFormat during the presave event"""