diff --git a/.gitmodules b/.gitmodules
index df9c8f83d..f0c6ba8db 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -15,7 +15,7 @@
 	url = https://github.com/maxbrunsfeld/tree-sitter.git
 [submodule "prototype/External/tree-sitter-javascript"]
 	path = prototype/External/tree-sitter-javascript
-	url = https://github.com/maxbrunsfeld/tree-sitter-javascript.git
+	url = https://github.com/joshvera/tree-sitter-javascript.git
 [submodule "prototype/External/tree-sitter-c"]
 	path = prototype/External/tree-sitter-c
 	url = https://github.com/robrix/tree-sitter-c.git
diff --git a/app/Main.hs b/app/Main.hs
index c115f906a..fc58dd39f 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -13,6 +13,7 @@ import qualified Data.Map as Map
 import qualified Data.ByteString.Char8 as ByteString
 import Data.Set hiding (split)
 import Options.Applicative
+import System.FilePath
 
 import Foreign
 import Foreign.C
@@ -20,6 +21,7 @@ import Foreign.C.Types
 
 data TSLanguage = TsLanguage deriving (Show, Eq)
 foreign import ccall "prototype/doubt-difftool/doubt-difftool-Bridging-Header.h ts_language_c" ts_language_c :: IO (Ptr TSLanguage)
+foreign import ccall "prototype/doubt-difftool/doubt-difftool-Bridging-Header.h ts_language_javascript" ts_language_javascript :: IO (Ptr TSLanguage)
 
 data TSDocument = TsDocument deriving (Show, Eq)
 foreign import ccall "prototype/External/tree-sitter/include/tree_sitter/runtime.h ts_document_make" ts_document_make :: IO (Ptr TSDocument)
@@ -64,10 +66,15 @@ main :: IO ()
 main = do
   arguments <- execParser opts
   output <- do
-    aContents <- readFile $ sourceA arguments
-    bContents <- readFile $ sourceB arguments
-    aTerm <- parseTreeSitterFile aContents
-    bTerm <- parseTreeSitterFile bContents
+    let (sourceAPath, sourceBPath) = (sourceA arguments, sourceB arguments)
+    aContents <- readFile sourceAPath
+    bContents <- readFile sourceBPath
+    language <- (parserForType . takeExtension) sourceAPath
+    (aTerm, bTerm) <- case language of
+      Just lang -> do aTerm <- parseTreeSitterFile lang aContents
+                      bTerm <- parseTreeSitterFile lang bContents
+                      return (aTerm, bTerm)
+      Nothing -> error ("Unsupported language extension in path: " ++ sourceAPath)
     let diff = interpret comparable aTerm bTerm in
       case output arguments of
         Unified -> unified diff aContents bContents
@@ -76,10 +83,15 @@ main = do
     opts = info (helper <*> arguments)
       (fullDesc <> progDesc "Diff some things" <> header "semantic-diff - diff semantically")
 
-parseTreeSitterFile :: String -> IO (Term String Info)
-parseTreeSitterFile contents = do
+parserForType mediaType = sequence $ case mediaType of
+    "h" -> Just ts_language_c
+    "c" -> Just ts_language_c
+    "js" -> Just ts_language_javascript
+    _ -> Nothing
+
+parseTreeSitterFile :: Ptr TSLanguage -> String -> IO (Term String Info)
+parseTreeSitterFile language contents = do
   document <- ts_document_make
-  language <- ts_language_c
   ts_document_set_language document language
   withCString contents (\source -> do
     ts_document_set_input_string document source
diff --git a/app/bridge.c b/app/bridge.c
index 088803a70..22d8bb428 100644
--- a/app/bridge.c
+++ b/app/bridge.c
@@ -12,6 +12,10 @@ TSLanguage *ts_language_c_use() {
 	return ts_language_c();
 }
 
+TSLanguage *ts_language_javascript_use() {
+	return ts_language_javascript();
+}
+
 const char *ts_node_p_name(const TSNode *node, const TSDocument *document) {
 	assert(node != NULL);
 	assert(node->data != NULL);
diff --git a/app/bridge.h b/app/bridge.h
index 63a502968..b33103ee2 100644
--- a/app/bridge.h
+++ b/app/bridge.h
@@ -1,6 +1,7 @@
 #include "tree_sitter/runtime.h"
 
 extern TSLanguage *ts_language_c();
+extern TSLanguage *ts_language_javascript();
 
 void ts_document_root_node_p(TSDocument *document, TSNode *outNode);
 
diff --git a/prototype/External/tree-sitter-javascript b/prototype/External/tree-sitter-javascript
index 74444328e..486c784ab 160000
--- a/prototype/External/tree-sitter-javascript
+++ b/prototype/External/tree-sitter-javascript
@@ -1 +1 @@
-Subproject commit 74444328e7910ea0d42a4a735b336a963e4b1105
+Subproject commit 486c784ab4cfff7839bfacc40543422c61ef9abb
diff --git a/semantic-diff.cabal b/semantic-diff.cabal
index b4a5c6bd6..3b94d017a 100644
--- a/semantic-diff.cabal
+++ b/semantic-diff.cabal
@@ -45,9 +45,13 @@ executable semantic-diff-exe
                      , semantic-diff
                      , bytestring
                      , optparse-applicative
+                     , filepath
   default-language:    Haskell2010
   extra-libraries:     bridge
-  extra-lib-dirs:      prototype/External/tree-sitter/out/Release, prototype/External/tree-sitter-c, .
+  extra-lib-dirs:      prototype/External/tree-sitter/out/Release
+                     , prototype/External/tree-sitter-c
+                     , prototype/External/tree-sitter-javascript
+                     , .
 
 test-suite semantic-diff-test
   type:                exitcode-stdio-1.0