hashable.patch

diff --git a/hashable.cabal b/hashable.cabal
index 4197060..1d3cd53 100644
--- a/hashable.cabal
+++ b/hashable.cabal
@@ -84,6 +84,9 @@ library
     , ghc-prim
     , text        >=0.12 && <1.3
 
+  if impl(ghcjs)
+    Build-depends:   ghcjs-base
+
   if impl(ghc >=9)
     build-depends: ghc-bignum ==1.0.* || ==1.2.*
 
diff --git a/src/Data/Hashable/Class.hs b/src/Data/Hashable/Class.hs
index c7dd8c5..036f450 100644
--- a/src/Data/Hashable/Class.hs
+++ b/src/Data/Hashable/Class.hs
@@ -5,6 +5,10 @@
 
 {-# LANGUAGE Trustworthy #-}
 
+#ifdef __GHCJS__
+{-# LANGUAGE JavaScriptFFI, UnboxedTuples, GHCForeignImportPrim #-}
+#endif
+
 #if __GLASGOW_HASKELL__ >= 801
 {-# LANGUAGE PolyKinds #-} -- For TypeRep instances
 #endif
@@ -72,7 +76,9 @@ import Data.Int (Int8, Int16, Int32, Int64)
 import Data.List (foldl')
 import Data.Ratio (Ratio, denominator, numerator)
 import qualified Data.Text as T
+#ifndef __GHCJS__
 import qualified Data.Text.Array as TA
+#endif
 import qualified Data.Text.Internal as T
 import qualified Data.Text.Lazy as TL
 import Data.Version (Version(..))
@@ -92,6 +98,9 @@ import qualified Data.Map as Map
 import qualified Data.Sequence as Seq
 import qualified Data.Set as Set
 import qualified Data.Tree as Tree
+#ifdef __GHCJS__
+import Data.JSString (JSString)
+#endif
 
 -- As we use qualified F.Foldable, we don't get warnings with newer base
 import qualified Data.Foldable as F
@@ -152,7 +161,11 @@ import GHC.Exts (Int (..), sizeofByteArray#)
 #  define MIN_VERSION_integer_gmp_1_0_0
 # endif
 
+#ifndef __GHCJS__
 import GHC.Exts (Int(..))
+#else
+import GHC.Exts (Int(..), Int#)
+#endif
 import GHC.Integer.GMP.Internals (Integer(..))
 # if defined(MIN_VERSION_integer_gmp_1_0_0)
 import GHC.Exts (sizeofByteArray#)
@@ -676,17 +689,31 @@ instance Hashable BSI.ShortByteString where
 #endif
 
 instance Hashable T.Text where
+#ifndef __GHCJS__
     hashWithSalt salt (T.Text arr off len) =
         hashByteArrayWithSalt (TA.aBA arr) (off `shiftL` 1) (len `shiftL` 1)
         (hashWithSalt salt len)
+#else
+    hashWithSalt salt (T.Text txt) =
+        hashByteArrayWithSalt ba (0 `shiftL` 1) (I# len `shiftL` 1)
+        (hashWithSalt salt (I# len))
+        where (# ba, len #) = js_textFromJSString txt
+#endif
 
 instance Hashable TL.Text where
     hashWithSalt salt = finalise . TL.foldlChunks step (SP salt 0)
       where
         finalise (SP s l) = hashWithSalt s l
+#ifndef __GHCJS__
         step (SP s l) (T.Text arr off len) = SP
             (hashByteArrayWithSalt (TA.aBA arr) (off `shiftL` 1) (len `shiftL` 1) s)
             (l + len)
+#else
+        step (SP s l) (T.Text txt) = SP
+            (hashByteArrayWithSalt ba (0 `shiftL` 1) (I# len `shiftL` 1) s)
+            (l + I# len)
+            where (# ba, len #) = js_textFromJSString txt
+#endif
 
 -- | Compute the hash of a ThreadId.
 hashThreadId :: ThreadId -> Int
@@ -880,6 +907,12 @@ instance Hashable1 Option where liftHashWithSalt h salt (Option a) = liftHashWit
 #endif
 #endif
 
+#ifdef __GHCJS__
+foreign import javascript unsafe
+  "h$textFromString"
+  js_textFromJSString :: JSString -> (# ByteArray#, Int# #)
+#endif
+
 -- instances for @Data.Functor.{Product,Sum,Compose}@, present
 -- in base-4.9 and onward.
 #if MIN_VERSION_base(4,9,0)