diff --git a/boot/base/GHC/Conc.hs b/boot/base/GHC/Conc.hs
index 68182a1..80dff2a 100644
--- a/boot/base/GHC/Conc.hs
+++ b/boot/base/GHC/Conc.hs
@@ -93,7 +93,7 @@ module GHC.Conc
         , asyncWriteBA
 #endif
 
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
         , Signal, HandlerFun, setHandler, runHandlers
 #endif
 
@@ -114,6 +114,6 @@ module GHC.Conc
 import GHC.Conc.IO
 import GHC.Conc.Sync
 
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
 import GHC.Conc.Signal
 #endif
diff --git a/boot/base/GHC/Conc/IO.hs b/boot/base/GHC/Conc/IO.hs
index 3a57c93..994921f 100644
--- a/boot/base/GHC/Conc/IO.hs
+++ b/boot/base/GHC/Conc/IO.hs
@@ -59,24 +59,26 @@ import GHC.Conc.Sync as Sync
 import GHC.Real ( fromIntegral )
 import System.Posix.Types
 
-#ifdef mingw32_HOST_OS
+#if defined(mingw32_HOST_OS)
 import qualified GHC.Conc.Windows as Windows
 import GHC.Conc.Windows (asyncRead, asyncWrite, asyncDoProc, asyncReadBA,
                          asyncWriteBA, ConsoleEvent(..), win32ConsoleHandler,
                          toWin32ConsoleEvent)
-#else
+#elif !defined(ghcjs_HOST_OS)
 import qualified GHC.Event.Thread as Event
 #endif
 
 ensureIOManagerIsRunning :: IO ()
-#ifndef mingw32_HOST_OS
-ensureIOManagerIsRunning = Event.ensureIOManagerIsRunning
-#else
+#if defined(mingw32_HOST_OS)
 ensureIOManagerIsRunning = Windows.ensureIOManagerIsRunning
+#elif defined(ghcjs_HOST_OS)
+ensureIOManagerIsRunning = return ()
+#else
+ensureIOManagerIsRunning = Event.ensureIOManagerIsRunning
 #endif
 
 ioManagerCapabilitiesChanged :: IO ()
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
 ioManagerCapabilitiesChanged = Event.ioManagerCapabilitiesChanged
 #else
 ioManagerCapabilitiesChanged = return ()
@@ -90,7 +92,7 @@ ioManagerCapabilitiesChanged = return ()
 -- that has been used with 'threadWaitRead', use 'closeFdWith'.
 threadWaitRead :: Fd -> IO ()
 threadWaitRead fd
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
   | threaded  = Event.threadWaitRead fd
 #endif
   | otherwise = IO $ \s ->
@@ -106,7 +108,7 @@ threadWaitRead fd
 -- that has been used with 'threadWaitWrite', use 'closeFdWith'.
 threadWaitWrite :: Fd -> IO ()
 threadWaitWrite fd
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
   | threaded  = Event.threadWaitWrite fd
 #endif
   | otherwise = IO $ \s ->
@@ -120,7 +122,7 @@ threadWaitWrite fd
 -- in the file descriptor.
 threadWaitReadSTM :: Fd -> IO (Sync.STM (), IO ())
 threadWaitReadSTM fd 
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
   | threaded  = Event.threadWaitReadSTM fd
 #endif
   | otherwise = do
@@ -139,7 +141,7 @@ threadWaitReadSTM fd
 -- in the file descriptor.
 threadWaitWriteSTM :: Fd -> IO (Sync.STM (), IO ())
 threadWaitWriteSTM fd 
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
   | threaded  = Event.threadWaitWriteSTM fd
 #endif
   | otherwise = do
@@ -164,7 +166,7 @@ closeFdWith :: (Fd -> IO ()) -- ^ Low-level action that performs the real close.
             -> Fd            -- ^ File descriptor to close.
             -> IO ()
 closeFdWith close fd
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
   | threaded  = Event.closeFdWith close fd
 #endif
   | otherwise = close fd
@@ -178,9 +180,9 @@ closeFdWith close fd
 --
 threadDelay :: Int -> IO ()
 threadDelay time
-#ifdef mingw32_HOST_OS
+#if defined(mingw32_HOST_OS)
   | threaded  = Windows.threadDelay time
-#else
+#elif !defined(ghcjs_HOST_OS)
   | threaded  = Event.threadDelay time
 #endif
   | otherwise = IO $ \s ->
@@ -193,9 +195,9 @@ threadDelay time
 --
 registerDelay :: Int -> IO (TVar Bool)
 registerDelay usecs
-#ifdef mingw32_HOST_OS
+#if defined(mingw32_HOST_OS)
   | threaded = Windows.registerDelay usecs
-#else
+#elif !defined(ghcjs_HOST_OS)
   | threaded = Event.registerDelay usecs
 #endif
   | otherwise = error "registerDelay: requires -threaded"
diff --git a/boot/base/GHC/Conc/Windows.hs b/boot/base/GHC/Conc/Windows.hs
index 7935a8a..979ed6f 100644
--- a/boot/base/GHC/Conc/Windows.hs
+++ b/boot/base/GHC/Conc/Windows.hs
@@ -20,6 +20,9 @@
 
 -- #not-home
 module GHC.Conc.Windows
+#ifdef ghcjs_HOST_OS
+       () where
+#else
        ( ensureIOManagerIsRunning
 
        -- * Waiting
@@ -337,3 +340,4 @@ foreign import ccall unsafe "sendIOManagerEvent" -- in the RTS (ThrIOManager.c)
 foreign import WINDOWS_CCONV "WaitForSingleObject"
    c_WaitForSingleObject :: HANDLE -> DWORD -> IO DWORD
 
+#endif
diff --git a/boot/base/GHC/Event.hs b/boot/base/GHC/Event.hs
index 436914c..c41abfc 100644
--- a/boot/base/GHC/Event.hs
+++ b/boot/base/GHC/Event.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE CPP #-}
 
 -- ----------------------------------------------------------------------------
 -- | This module provides scalable event notification for file
@@ -10,6 +11,9 @@
 -- ----------------------------------------------------------------------------
 
 module GHC.Event
+#ifdef ghcjs_HOST_OS
+    ( ) where
+#else
     ( -- * Types
       EventManager
     , TimerManager
@@ -43,3 +47,4 @@ import GHC.Event.TimerManager (TimeoutCallback, TimeoutKey, registerTimeout,
                                updateTimeout, unregisterTimeout, TimerManager)
 import GHC.Event.Thread (getSystemEventManager, getSystemTimerManager)
 
+#endif
diff --git a/boot/base/GHC/Event/Manager.hs b/boot/base/GHC/Event/Manager.hs
index 11b01ad..4de059b 100644
--- a/boot/base/GHC/Event/Manager.hs
+++ b/boot/base/GHC/Event/Manager.hs
@@ -19,6 +19,9 @@
 -- polling if available. Otherwise we use multi-shot polling.
 
 module GHC.Event.Manager
+#ifdef ghcjs_HOST_OS
+    () where
+#else
     ( -- * Types
       EventManager
 
@@ -497,3 +500,6 @@ nullToNothing xs@(_:_) = Just xs
 
 unless :: Monad m => Bool -> m () -> m ()
 unless p = when (not p)
+
+#endif
+
diff --git a/boot/base/GHC/Event/Thread.hs b/boot/base/GHC/Event/Thread.hs
index d4b6792..5983d0e 100644
--- a/boot/base/GHC/Event/Thread.hs
+++ b/boot/base/GHC/Event/Thread.hs
@@ -1,7 +1,11 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE BangPatterns, NoImplicitPrelude #-}
+{-# LANGUAGE CPP #-}
 
 module GHC.Event.Thread
+#ifdef ghcjs_HOST_OS
+    ( ) where
+#else
     ( getSystemEventManager
     , getSystemTimerManager
     , ensureIOManagerIsRunning
@@ -360,3 +364,6 @@ foreign import ccall unsafe "setIOManagerControlFd"
 
 foreign import ccall unsafe "setTimerManagerControlFd"
    c_setTimerManagerControlFd :: CInt -> IO ()
+
+#endif
+
diff --git a/boot/base/GHC/Event/TimerManager.hs b/boot/base/GHC/Event/TimerManager.hs
index c1ab64c..2184869 100644
--- a/boot/base/GHC/Event/TimerManager.hs
+++ b/boot/base/GHC/Event/TimerManager.hs
@@ -8,6 +8,9 @@
   #-}
 
 module GHC.Event.TimerManager
+#ifdef ghcjs_HOST_OS
+    () where
+#else
     ( -- * Types
       TimerManager
 
@@ -241,3 +244,4 @@ updateTimeout mgr (TK key) us = do
 editTimeouts :: TimerManager -> TimeoutEdit -> IO ()
 editTimeouts mgr g = atomicModifyIORef' (emTimeouts mgr) $ \tq -> (g tq, ())
 
+#endif
diff --git a/boot/base/GHC/IO/Encoding.hs b/boot/base/GHC/IO/Encoding.hs
index 31683b4..c730184 100644
--- a/boot/base/GHC/IO/Encoding.hs
+++ b/boot/base/GHC/IO/Encoding.hs
@@ -140,8 +140,11 @@ mkGlobal x = unsafePerformIO $ do
 
 -- | @since 4.5.0.0
 initLocaleEncoding, initFileSystemEncoding, initForeignEncoding :: TextEncoding
-
-#if !defined(mingw32_HOST_OS)
+#if defined(ghcjs_HOST_OS)
+initLocaleEncoding     = utf8
+initFileSystemEncoding = utf8
+initForeignEncoding    = utf8
+#elif !defined(mingw32_HOST_OS)
 -- It is rather important that we don't just call Iconv.mkIconvEncoding here
 -- because some iconvs (in particular GNU iconv) will brokenly UTF-8 encode
 -- lone surrogates without complaint.
diff --git a/boot/base/GHC/IO/Encoding/CodePage/API.hs b/boot/base/GHC/IO/Encoding/CodePage/API.hs
index 966a690..84b2db6 100644
--- a/boot/base/GHC/IO/Encoding/CodePage/API.hs
+++ b/boot/base/GHC/IO/Encoding/CodePage/API.hs
@@ -29,6 +29,7 @@ import GHC.ForeignPtr (castForeignPtr)
 
 import System.Posix.Internals
 
+#ifndef ghcjs_HOST_OS
 
 c_DEBUG_DUMP :: Bool
 c_DEBUG_DUMP = False
@@ -426,3 +427,8 @@ cpRecode try' is_valid_prefix max_i_size min_o_size iscale oscale = go
             -- Must have interpreted all given bytes successfully
             -- We need to iterate until we have consumed the complete contents of the buffer
             Right wrote_elts -> go (bufferRemove n ibuf) (obuf { bufR = bufR obuf + wrote_elts })
+
+#else
+mkCodePageEncoding :: String
+mkCodePageEncoding = ""
+#endif
diff --git a/boot/base/GHC/IO/FD.hs b/boot/base/GHC/IO/FD.hs
index 610c9ea..774ac69 100644
--- a/boot/base/GHC/IO/FD.hs
+++ b/boot/base/GHC/IO/FD.hs
@@ -500,6 +500,10 @@ indicates that there's no data, we call threadWaitRead.
 
 readRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int
 readRawBufferPtr loc !fd buf off len
+#ifdef ghcjs_HOST_OS
+  = fmap fromIntegral . uninterruptibleMask_ $
+    throwErrnoIfMinus1 loc (c_read (fdFD fd) (buf `plusPtr` off) len)
+#else
   | isNonBlocking fd = unsafe_read -- unsafe is ok, it can't block
   | otherwise    = do r <- throwErrnoIfMinus1 loc
                                 (unsafe_fdReady (fdFD fd) 0 0 0)
@@ -513,10 +517,19 @@ readRawBufferPtr loc !fd buf off len
     read        = if threaded then safe_read else unsafe_read
     unsafe_read = do_read (c_read (fdFD fd) (buf `plusPtr` off) len)
     safe_read   = do_read (c_safe_read (fdFD fd) (buf `plusPtr` off) len)
+#endif
 
 -- return: -1 indicates EOF, >=0 is bytes read
 readRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int
 readRawBufferPtrNoBlock loc !fd buf off len
+#ifdef ghcjs_HOST_OS
+  = uninterruptibleMask_ $ do
+      r <- throwErrnoIfMinus1 loc (c_read (fdFD fd) (buf `plusPtr` off) len)
+      case r of
+       (-1) -> return 0
+       0    -> return (-1)
+       n    -> return (fromIntegral n)
+#else
   | isNonBlocking fd  = unsafe_read -- unsafe is ok, it can't block
   | otherwise    = do r <- unsafe_fdReady (fdFD fd) 0 0 0
                       if r /= 0 then safe_read
@@ -530,9 +543,14 @@ readRawBufferPtrNoBlock loc !fd buf off len
                        n    -> return (fromIntegral n)
    unsafe_read  = do_read (c_read (fdFD fd) (buf `plusPtr` off) len)
    safe_read    = do_read (c_safe_read (fdFD fd) (buf `plusPtr` off) len)
+#endif
 
 writeRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
 writeRawBufferPtr loc !fd buf off len
+#ifdef ghcjs_HOST_OS
+  = fmap fromIntegral . uninterruptibleMask_ $
+    throwErrnoIfMinus1 loc (c_write (fdFD fd) (buf `plusPtr` off) len)
+#else
   | isNonBlocking fd = unsafe_write -- unsafe is ok, it can't block
   | otherwise   = do r <- unsafe_fdReady (fdFD fd) 1 0 0
                      if r /= 0
@@ -545,9 +563,17 @@ writeRawBufferPtr loc !fd buf off len
     write         = if threaded then safe_write else unsafe_write
     unsafe_write  = do_write (c_write (fdFD fd) (buf `plusPtr` off) len)
     safe_write    = do_write (c_safe_write (fdFD fd) (buf `plusPtr` off) len)
+#endif
 
 writeRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
 writeRawBufferPtrNoBlock loc !fd buf off len
+#ifdef ghcjs_HOST_OS
+  = uninterruptibleMask_ $ do
+      r <- throwErrnoIfMinus1 loc (c_write (fdFD fd) (buf `plusPtr` off) len)
+      case r of
+        (-1) -> return 0
+        n    -> return (fromIntegral n)
+#else
   | isNonBlocking fd = unsafe_write -- unsafe is ok, it can't block
   | otherwise   = do r <- unsafe_fdReady (fdFD fd) 1 0 0
                      if r /= 0 then write
@@ -560,9 +586,14 @@ writeRawBufferPtrNoBlock loc !fd buf off len
     write         = if threaded then safe_write else unsafe_write
     unsafe_write  = do_write (c_write (fdFD fd) (buf `plusPtr` off) len)
     safe_write    = do_write (c_safe_write (fdFD fd) (buf `plusPtr` off) len)
+#endif
 
 isNonBlocking :: FD -> Bool
+#ifdef ghcjs_HOST_OS
+isNonBlocking _  = True
+#else
 isNonBlocking fd = fdIsNonBlocking fd /= 0
+#endif
 
 foreign import ccall unsafe "fdReady"
   unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
@@ -646,7 +677,7 @@ foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
 -- -----------------------------------------------------------------------------
 -- utils
 
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
 throwErrnoIfMinus1RetryOnBlock  :: String -> IO CSsize -> IO CSsize -> IO CSsize
 throwErrnoIfMinus1RetryOnBlock loc f on_block  =
   do
diff --git a/boot/base/GHC/Stack.hsc b/boot/base/GHC/Stack.hsc
index 0aa4d17..ee56621 100644
--- a/boot/base/GHC/Stack.hsc
+++ b/boot/base/GHC/Stack.hsc
@@ -15,7 +15,7 @@
 -- @since 4.5.0.0
 -----------------------------------------------------------------------------
 
-{-# LANGUAGE UnboxedTuples, MagicHash, NoImplicitPrelude #-}
+{-# LANGUAGE CPP, UnboxedTuples, MagicHash, NoImplicitPrelude #-}
 module GHC.Stack (
     -- * Call stack
     currentCallStack,
@@ -63,6 +63,22 @@ getCCSOf obj = IO $ \s ->
    case getCCSOf## obj s of
      (## s', addr ##) -> (## s', Ptr addr ##)
 
+##ifdef ghcjs_HOST_OS
+ccsCC :: Ptr CostCentreStack -> IO (Ptr CostCentre)
+ccsCC p = peekByteOff p 4
+
+ccsParent :: Ptr CostCentreStack -> IO (Ptr CostCentreStack)
+ccsParent p = peekByteOff p 8
+
+ccLabel :: Ptr CostCentre -> IO CString
+ccLabel p = peekByteOff p 4
+
+ccModule :: Ptr CostCentre -> IO CString
+ccModule p = peekByteOff p 8
+
+ccSrcSpan :: Ptr CostCentre -> IO CString
+ccSrcSpan p = peekByteOff p 12
+##else
 ccsCC :: Ptr CostCentreStack -> IO (Ptr CostCentre)
 ccsCC p = (# peek CostCentreStack, cc) p
 
@@ -77,6 +93,7 @@ ccModule p = (# peek CostCentre, module) p
 
 ccSrcSpan :: Ptr CostCentre -> IO CString
 ccSrcSpan p = (# peek CostCentre, srcloc) p
+##endif
 
 -- | returns a '[String]' representing the current call stack.  This
 -- can be useful for debugging.
diff --git a/boot/base/GHC/Stats.hsc b/boot/base/GHC/Stats.hsc
index 7bcc221..378ca67 100644
--- a/boot/base/GHC/Stats.hsc
+++ b/boot/base/GHC/Stats.hsc
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE RecordWildCards #-}
@@ -100,6 +101,28 @@ getGCStats = do
     "getGCStats: GC stats not enabled. Use `+RTS -T -RTS' to enable them."
     Nothing
     Nothing
+##ifdef ghcjs_HOST_OS
+  allocaBytes 144 $ \p -> do
+    getGCStats_ p
+    bytesAllocated <- peekByteOff p 0
+    numGcs <- peekByteOff p 8
+    numByteUsageSamples <- peekByteOff p 16
+    maxBytesUsed <- peekByteOff p 24
+    cumulativeBytesUsed <- peekByteOff p 32
+    bytesCopied <- peekByteOff p 40
+    currentBytesUsed <- peekByteOff p 48
+    currentBytesSlop <- peekByteOff p 56
+    maxBytesSlop <- peekByteOff p 64
+    peakMegabytesAllocated <- peekByteOff p 72
+    mutatorCpuSeconds <- peekByteOff p 80
+    mutatorWallSeconds <- peekByteOff p 88
+    gcCpuSeconds <- peekByteOff p 96
+    gcWallSeconds <- peekByteOff p 104
+    cpuSeconds <- peekByteOff p 112
+    wallSeconds <- peekByteOff p 120
+    parTotBytesCopied <- peekByteOff p 128
+    parMaxBytesCopied <- peekByteOff p 136
+##else
   allocaBytes (#size GCStats) $ \p -> do
     getGCStats_ p
     bytesAllocated <- (# peek GCStats, bytes_allocated) p
@@ -124,6 +147,7 @@ getGCStats = do
     wallSeconds <- (# peek GCStats, wall_seconds) p
     parTotBytesCopied <- (# peek GCStats, par_tot_bytes_copied) p
     parMaxBytesCopied <- (# peek GCStats, par_max_bytes_copied) p
+##endif
     return GCStats { .. }
 
 {-
diff --git a/boot/base/GHC/TopHandler.hs b/boot/base/GHC/TopHandler.hs
index d7c0038..9518de3 100644
--- a/boot/base/GHC/TopHandler.hs
+++ b/boot/base/GHC/TopHandler.hs
@@ -68,7 +68,9 @@ runMainIO main =
       topHandler
 
 install_interrupt_handler :: IO () -> IO ()
-#ifdef mingw32_HOST_OS
+#if defined(ghcjs_HOST_OS)
+install_interrupt_handler _ = return ()
+#elif defined(mingw32_HOST_OS)
 install_interrupt_handler handler = do
   _ <- GHC.ConsoleHandler.installHandler $
      Catch $ \event ->
@@ -182,7 +184,7 @@ unreachable :: IO a
 unreachable = fail "If you can read this, shutdownHaskellAndExit did not exit."
 
 exitHelper :: CInt -> Int -> IO a
-#ifdef mingw32_HOST_OS
+#if defined(mingw32_HOST_OS) || defined(ghcjs_HOST_OS)
 exitHelper exitKind r =
   shutdownHaskellAndExit (fromIntegral r) exitKind >> unreachable
 #else
@@ -204,7 +206,7 @@ foreign import ccall "shutdownHaskellAndSignal"
 
 exitInterrupted :: IO a
 exitInterrupted =
-#ifdef mingw32_HOST_OS
+#if defined(mingw32_HOST_OS) || defined(ghcjs_HOST_OS)
   safeExit 252
 #else
   -- we must exit via the default action for SIGINT, so that the
diff --git a/boot/base/GHC/Windows.hs b/boot/base/GHC/Windows.hs
index 45032d5..7f1e83b 100644
--- a/boot/base/GHC/Windows.hs
+++ b/boot/base/GHC/Windows.hs
@@ -21,6 +21,10 @@
 -----------------------------------------------------------------------------
 
 module GHC.Windows (
+#ifdef ghcjs_HOST_OS
+                   ) where
+
+#else
         -- * Types
         BOOL,
         LPBOOL,
@@ -194,3 +198,5 @@ foreign import WINDOWS_CCONV unsafe "windows.h LocalFree"
 -- | Get the last system error produced in the current thread.
 foreign import WINDOWS_CCONV unsafe "windows.h GetLastError"
     getLastError :: IO ErrCode
+
+#endif
diff --git a/boot/base/System/CPUTime.hsc b/boot/base/System/CPUTime.hsc
index e09439c..2640ac9 100644
--- a/boot/base/System/CPUTime.hsc
+++ b/boot/base/System/CPUTime.hsc
@@ -24,6 +24,14 @@ module System.CPUTime
          cpuTimePrecision  -- :: Integer
         ) where
 
+##ifdef ghcjs_HOST_OS
+getCPUTime :: IO Integer
+getCPUTime = return 0
+
+cpuTimePrecision :: Integer
+cpuTimePrecision = 1
+##else
+
 import Data.Ratio
 
 import Foreign
@@ -159,3 +167,4 @@ foreign import ccall unsafe clk_tck :: CLong
 
 clockTicks :: Int
 clockTicks = fromIntegral clk_tck
+##endif
diff --git a/boot/base/System/Environment/ExecutablePath.hsc b/boot/base/System/Environment/ExecutablePath.hsc
index 410e3ac..34f0a2a 100644
--- a/boot/base/System/Environment/ExecutablePath.hsc
+++ b/boot/base/System/Environment/ExecutablePath.hsc
@@ -18,6 +18,13 @@
 
 module System.Environment.ExecutablePath ( getExecutablePath ) where
 
+##if defined(ghcjs_HOST_OS)
+
+getExecutablePath :: IO FilePath
+getExecutablePath = return "a.jsexe"
+
+##else
+
 -- The imports are purposely kept completely disjoint to prevent edits
 -- to one OS implementation from breaking another.
 
@@ -173,3 +180,5 @@ getExecutablePath =
 --------------------------------------------------------------------------------
 
 #endif
+
+##endif
\ No newline at end of file
diff --git a/boot/base/System/Posix/Internals.hs b/boot/base/System/Posix/Internals.hs
index c49e613..f52326a 100644
--- a/boot/base/System/Posix/Internals.hs
+++ b/boot/base/System/Posix/Internals.hs
@@ -1,6 +1,9 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE CPP, NoImplicitPrelude, CApiFFI #-}
 {-# OPTIONS_HADDOCK hide #-}
+#ifdef ghcjs_HOST_OS
+{-# LANGUAGE JavaScriptFFI #-}
+#endif
 
 -----------------------------------------------------------------------------
 -- |
@@ -134,7 +137,7 @@ ioe_unknownfiletype = IOError Nothing UnsupportedOperation "fdType"
                         Nothing
 
 fdGetMode :: FD -> IO IOMode
-#if defined(mingw32_HOST_OS) || defined(__MINGW32__)
+#if defined(mingw32_HOST_OS) || defined(__MINGW32__) || defined(ghcjs_HOST_OS)
 fdGetMode _ = do
     -- We don't have a way of finding out which flags are set on FDs
     -- on Windows, so make a handle that thinks that anything goes.
@@ -314,7 +317,7 @@ foreign import ccall unsafe "consUtils.h is_console__"
 -- Turning on non-blocking for a file descriptor
 
 setNonBlockingFD :: FD -> Bool -> IO ()
-#if !defined(mingw32_HOST_OS) && !defined(__MINGW32__)
+#if !defined(mingw32_HOST_OS) && !defined(__MINGW32__) && !defined(ghcjs_HOST_OS)
 setNonBlockingFD fd set = do
   flags <- throwErrnoIfMinus1Retry "setNonBlockingFD"
                  (c_fcntl_read fd const_f_getfl)
@@ -336,7 +339,7 @@ setNonBlockingFD _ _ = return ()
 -- -----------------------------------------------------------------------------
 -- Set close-on-exec for a file descriptor
 
-#if !defined(mingw32_HOST_OS) && !defined(__MINGW32__)
+#if !defined(mingw32_HOST_OS) && !defined(__MINGW32__) && !defined(ghcjs_HOST_OS)
 setCloseOnExec :: FD -> IO ()
 setCloseOnExec fd = do
   throwErrnoIfMinus1_ "setCloseOnExec" $
@@ -352,6 +355,139 @@ type CFilePath = CString
 type CFilePath = CWString
 #endif
 
+#ifdef ghcjs_HOST_OS
+
+foreign import javascript interruptible "h$base_access($1_1,$1_2,$2,$c);"
+    c_access :: CString -> CInt -> IO CInt
+foreign import javascript interruptible "h$base_chmod($1_1,$1_2,$2,$c);"
+    c_chmod :: CString -> CMode -> IO CInt
+foreign import javascript interruptible "h$base_close($1,$c);"
+    c_close :: CInt -> IO CInt
+foreign import javascript interruptible "h$base_creat($1,$c);"
+    c_creat :: CString -> CMode -> IO CInt
+foreign import javascript interruptible "h$base_dup($1,$c);"
+    c_dup :: CInt -> IO CInt
+foreign import javascript interruptible "h$base_dup2($1,$2,$c);"
+    c_dup2 :: CInt -> CInt -> IO CInt
+foreign import javascript interruptible "h$base_fstat($1,$2_1,$2_2,$c);" -- fixme wrong type
+    c_fstat :: CInt -> Ptr CStat -> IO CInt
+foreign import javascript unsafe "$r = h$base_isatty($1);"
+    c_isatty :: CInt -> IO CInt
+foreign import javascript interruptible "h$base_lseek($1,$2_1,$2_2,$3,$c);"
+   c_lseek :: CInt -> Int64 -> CInt -> IO Int64
+foreign import javascript interruptible "h$base_lstat($1_1,$1_2,$2_1,$2_2,$c);" -- fixme wrong type
+   lstat :: CFilePath -> Ptr CStat -> IO CInt
+foreign import javascript interruptible "h$base_open($1_1,$1_2,$2,$3,$c);"
+   c_open :: CFilePath -> CInt -> CMode -> IO CInt
+foreign import javascript interruptible "h$base_open($1_1,$1_2,$2,$3,$c);"
+   c_safe_open :: CFilePath -> CInt -> CMode -> IO CInt
+foreign import javascript interruptible "h$base_read($1,$2_1,$2_2,$3,$c);"
+   c_read :: CInt -> Ptr Word8 -> CSize -> IO CSsize
+foreign import javascript interruptible "h$base_read($1,$2_1,$2_2,$3,$c);"
+   c_safe_read :: CInt -> Ptr Word8 -> CSize -> IO CSsize
+foreign import javascript interruptible "h$base_stat($1_1,$1_2,$2_1,$2_2,$c);" -- fixme wrong type
+   c_stat :: CFilePath -> Ptr CStat -> IO CInt
+foreign import javascript unsafe "$r = h$base_umask($1);"
+   c_umask :: CMode -> IO CMode
+foreign import javascript interruptible "h$base_write($1,$2_1,$2_2,$3,$c);"
+   c_write :: CInt -> Ptr Word8 -> CSize -> IO CSsize
+foreign import javascript interruptible "h$base_write($1,$2_1,$2_2,$3,$c);"
+   c_safe_write :: CInt -> Ptr Word8 -> CSize -> IO CSsize
+foreign import javascript interruptible "h$base_ftruncate($1,$2_1,$2_2,$c);" -- fixme COff
+   c_ftruncate :: CInt -> Int64 -> IO CInt
+foreign import javascript interruptible "h$base_unlink($1_1,$1_2,$c);"
+   c_unlink :: CString -> IO CInt
+foreign import javascript unsafe "$r = h$base_getpid();"
+   c_getpid :: IO CPid
+-- foreign import ccall unsafe "HsBase.h fork"
+--   c_fork :: IO CPid 
+foreign import javascript interruptible "h$base_link($1_1,$1_2,$2_1,$2_2,$c);"
+   c_link :: CString -> CString -> IO CInt
+foreign import javascript interruptible "h$base_mkfifo($1_1,$1_2,$2,$c);"
+   c_mkfifo :: CString -> CMode -> IO CInt
+-- foreign import javascript interruptible "h$base_pipe($1_1,$1_2,$c);"
+--   c_pipe :: Ptr CInt -> IO CInt
+foreign import javascript unsafe "$r = h$base_sigemptyset($1_1,$1_2);"
+   c_sigemptyset :: Ptr CSigset -> IO CInt
+foreign import javascript unsafe "$r = h$base_sigaddset($1_1,$1_2,$2);"
+   c_sigaddset :: Ptr CSigset -> CInt -> IO CInt
+foreign import javascript unsafe "$r = h$base_sigprocmask($1,$2_1,$2_2,$3_1,$3_2);"
+   c_sigprocmask :: CInt -> Ptr CSigset -> Ptr CSigset -> IO CInt
+foreign import javascript unsafe "$r = h$base_tcgetattr($1,$2_1,$2_2);"
+   c_tcgetattr :: CInt -> Ptr CTermios -> IO CInt
+foreign import javascript unsafe "$r = h$base_tcsetattr($1,$2,$3_1,$3_2);"
+   c_tcsetattr :: CInt -> CInt -> Ptr CTermios -> IO CInt
+foreign import javascript unsafe "$r = h$base_utime($1_1,$1_2,$2_1,$2_2);" -- should this be async?
+   c_utime :: CString -> Ptr CUtimbuf -> IO CInt
+foreign import javascript interruptible "h$base_waitpid($1,$2_1,$2_2,$3,$c);"
+   c_waitpid :: CPid -> Ptr CInt -> CInt -> IO CPid
+
+foreign import javascript unsafe "$r = h$base_o_rdonly;"   o_RDONLY   :: CInt
+foreign import javascript unsafe "$r = h$base_o_wronly;"   o_WRONLY   :: CInt
+foreign import javascript unsafe "$r = h$base_o_rdwr;"     o_RDWR     :: CInt
+foreign import javascript unsafe "$r = h$base_o_append;"   o_APPEND   :: CInt
+foreign import javascript unsafe "$r = h$base_o_creat;"    o_CREAT    :: CInt
+foreign import javascript unsafe "$r = h$base_o_excl;"     o_EXCL     :: CInt
+foreign import javascript unsafe "$r = h$base_o_trunc;"    o_TRUNC    :: CInt
+foreign import javascript unsafe "$r = h$base_o_noctty;"   o_NOCTTY   :: CInt
+foreign import javascript unsafe "$r = h$base_o_nonblock;" o_NONBLOCK :: CInt
+foreign import javascript unsafe "$r = h$base_o_binary;"   o_BINARY   :: CInt
+
+foreign import javascript unsafe "$r = h$base_c_s_isreg($1);"  c_s_isreg  :: CMode -> CInt
+foreign import javascript unsafe "$r = h$base_c_s_ischr($1);"  c_s_ischr  :: CMode -> CInt
+foreign import javascript unsafe "$r = h$base_c_s_isblk($1);"  c_s_isblk  :: CMode -> CInt
+foreign import javascript unsafe "$r = h$base_c_s_isdir($1);"  c_s_isdir  :: CMode -> CInt
+foreign import javascript unsafe "$r = h$base_c_s_isfifo($1);" c_s_isfifo :: CMode -> CInt
+
+s_isreg  :: CMode -> Bool
+s_isreg cm = c_s_isreg cm /= 0
+s_ischr  :: CMode -> Bool
+s_ischr cm = c_s_ischr cm /= 0
+s_isblk  :: CMode -> Bool
+s_isblk cm = c_s_isblk cm /= 0
+s_isdir  :: CMode -> Bool
+s_isdir cm = c_s_isdir cm /= 0
+s_isfifo :: CMode -> Bool
+s_isfifo cm = c_s_isfifo cm /= 0
+
+foreign import javascript unsafe "$r = h$base_sizeof_stat;" sizeof_stat :: Int
+foreign import javascript unsafe "h$base_st_mtime($1_1,$1_2)" st_mtime :: Ptr CStat -> IO CTime
+foreign import javascript unsafe "$r1 = h$base_st_size($1_1,$1_2); $r2 = h$ret1;" st_size :: Ptr CStat -> IO Int64
+foreign import javascript unsafe "$r = h$base_st_mode($1_1,$1_2);" st_mode :: Ptr CStat -> IO CMode
+foreign import javascript unsafe "$r = h$base_st_dev($1_1,$1_2);" st_dev :: Ptr CStat -> IO CDev
+foreign import javascript unsafe "$r1 = h$base_st_ino($1_1,$1_2); $r2 = h$ret1;" st_ino :: Ptr CStat -> IO CIno
+
+foreign import javascript unsafe "$r = h$base_echo;"            const_echo :: CInt
+foreign import javascript unsafe "$r = h$base_tcsanow;"         const_tcsanow :: CInt
+foreign import javascript unsafe "$r = h$base_icanon;"          const_icanon :: CInt
+foreign import javascript unsafe "$r = h$base_vmin;"            const_vmin   :: CInt
+foreign import javascript unsafe "$r = h$base_vtime;"           const_vtime  :: CInt
+foreign import javascript unsafe "$r = h$base_sigttou;"         const_sigttou :: CInt
+foreign import javascript unsafe "$r = h$base_sig_block;"       const_sig_block :: CInt
+foreign import javascript unsafe "$r = h$base_sig_setmask;"     const_sig_setmask :: CInt
+foreign import javascript unsafe "$r = h$base_f_getfl;"         const_f_getfl :: CInt
+foreign import javascript unsafe "$r = h$base_f_setfl;"         const_f_setfl :: CInt
+foreign import javascript unsafe "$r = h$base_f_setfd;"         const_f_setfd :: CInt
+foreign import javascript unsafe "$r = h$base_fd_cloexec;"      const_fd_cloexec :: CLong
+foreign import javascript unsafe "$r = h$base_sizeof_termios;"  sizeof_termios :: Int
+foreign import javascript unsafe "$r = h$base_sizeof_sigset_t;" sizeof_sigset_t :: Int
+foreign import javascript unsafe "$r = h$base_lflag($1_1,$1_2);"           c_lflag :: Ptr CTermios -> IO CTcflag
+foreign import javascript unsafe "h$base_poke_lflag($1_1,$1_2,$2);"      poke_c_lflag :: Ptr CTermios -> CTcflag -> IO ()
+foreign import javascript unsafe "$r1 = h$base_ptr_c_cc($1_1,$1_2); $r2 = h$ret_1;"   ptr_c_cc  :: Ptr CTermios -> IO (Ptr Word8)
+s_issock :: CMode -> Bool
+s_issock cmode = c_s_issock cmode /= 0
+foreign import javascript unsafe "h$base_c_s_issock($1)"          c_s_issock :: CMode -> CInt
+foreign import javascript unsafe "$r = h$base_default_buffer_size;" dEFAULT_BUFFER_SIZE :: Int
+foreign import javascript unsafe "$r = h$base_SEEK_CUR;"            sEEK_CUR :: CInt
+foreign import javascript unsafe "$r = h$base_SEEK_SET;"            sEEK_SET :: CInt
+foreign import javascript unsafe "$r = h$base_SEEK_END"             sEEK_END :: CInt
+
+-- fixme, unclear if these can be supported, remove?
+foreign import javascript unsafe "$r = h$base_c_fcntl_read($1,$2)"            c_fcntl_read  :: CInt -> CInt -> IO CInt
+foreign import javascript unsafe "$r = h$base_c_fcntl_write($1,$2,$3);"       c_fcntl_write :: CInt -> CInt -> CLong -> IO CInt
+foreign import javascript unsafe "$r = h$base_c_fcntl_lock($1,$2,$3_1,$3_2);" c_fcntl_lock  :: CInt -> CInt -> Ptr CFLock -> IO CInt
+
+#else
 foreign import ccall unsafe "HsBase.h access"
    c_access :: CString -> CInt -> IO CInt
 
@@ -551,6 +687,8 @@ foreign import capi  unsafe "stdio.h value SEEK_CUR" sEEK_CUR :: CInt
 foreign import capi  unsafe "stdio.h value SEEK_SET" sEEK_SET :: CInt
 foreign import capi  unsafe "stdio.h value SEEK_END" sEEK_END :: CInt
 
+#endif
+
 {-
 Note: CSsize
 
diff --git a/boot/base/System/Timeout.hs b/boot/base/System/Timeout.hs
index 73b5910..c4c5cdf 100644
--- a/boot/base/System/Timeout.hs
+++ b/boot/base/System/Timeout.hs
@@ -18,7 +18,7 @@
 
 module System.Timeout ( timeout ) where
 
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
 import Control.Monad
 import GHC.Event           (getSystemTimerManager,
                             registerTimeout, unregisterTimeout)
@@ -79,7 +79,7 @@ timeout :: Int -> IO a -> IO (Maybe a)
 timeout n f
     | n <  0    = fmap Just f
     | n == 0    = return Nothing
-#ifndef mingw32_HOST_OS
+#if !defined(mingw32_HOST_OS) && !defined(ghcjs_HOST_OS)
     | rtsSupportsBoundThreads = do
         -- In the threaded RTS, we use the Timer Manager to delay the
         -- (fairly expensive) 'forkIO' call until the timeout has expired.
diff --git a/boot/base/base.cabal b/boot/base/base.cabal
index 1172f2a..b949dc9 100644
--- a/boot/base/base.cabal
+++ b/boot/base/base.cabal
@@ -50,7 +50,7 @@ Flag integer-simple
 Flag integer-gmp
     Description: Use integer-gmp
     Manual: True
-    Default: False
+    Default: True
 
 Flag integer-gmp2
     Description: Use integer-gmp2
@@ -325,7 +325,7 @@ Library
         Typeable.h
 
     -- OS Specific
-    if os(windows)
+    if os(windows) && !impl(ghcjs)
         extra-libraries: wsock32, user32, shell32
         exposed-modules:
             GHC.IO.Encoding.CodePage.API
@@ -333,23 +333,24 @@ Library
             GHC.Conc.Windows
             GHC.Windows
     else
-        exposed-modules:
-            GHC.Event
-        other-modules:
-            GHC.Event.Arr
-            GHC.Event.Array
-            GHC.Event.Clock
-            GHC.Event.Control
-            GHC.Event.EPoll
-            GHC.Event.IntTable
-            GHC.Event.Internal
-            GHC.Event.KQueue
-            GHC.Event.Manager
-            GHC.Event.PSQ
-            GHC.Event.Poll
-            GHC.Event.Thread
-            GHC.Event.TimerManager
-            GHC.Event.Unique
+        if !impl(ghcjs)
+            exposed-modules:
+                GHC.Event
+            other-modules:
+                GHC.Event.Arr
+                GHC.Event.Array
+                GHC.Event.Clock
+                GHC.Event.Control
+                GHC.Event.EPoll
+                GHC.Event.IntTable
+                GHC.Event.Internal
+                GHC.Event.KQueue
+                GHC.Event.Manager
+                GHC.Event.PSQ
+                GHC.Event.Poll
+                GHC.Event.Thread
+                GHC.Event.TimerManager
+                GHC.Event.Unique
 
     -- We need to set the package key to base (without a version number)
     -- as it's magic.