diff --git a/dlls/jsproxy/jsproxy.spec b/dlls/jsproxy/jsproxy.spec
index 21943df1fc2..f557fe6c61d 100644
--- a/dlls/jsproxy/jsproxy.spec
+++ b/dlls/jsproxy/jsproxy.spec
@@ -1,5 +1,5 @@
-@ stub InternetInitializeAutoProxyDll
+@ stdcall InternetInitializeAutoProxyDll(long str str ptr ptr) JSPROXY_InternetInitializeAutoProxyDll
 @ stub InternetInitializeExAutoProxyDll
-@ stub InternetDeInitializeAutoProxyDll
+@ stdcall InternetDeInitializeAutoProxyDll(str long)
 @ stub InternetDeInitializeExAutoProxyDll
 @ stub InternetGetProxyInfo
diff --git a/dlls/jsproxy/main.c b/dlls/jsproxy/main.c
index fa9703d74a8..9305ff8ea92 100644
--- a/dlls/jsproxy/main.c
+++ b/dlls/jsproxy/main.c
@@ -23,12 +23,23 @@
 
 #include "windef.h"
 #include "winbase.h"
+#include "winnls.h"
+#include "wininet.h"
 #include "wine/debug.h"
 
 static HINSTANCE instance;
 
 WINE_DEFAULT_DEBUG_CHANNEL(jsproxy);
 
+static CRITICAL_SECTION cs_jsproxy;
+static CRITICAL_SECTION_DEBUG critsect_debug =
+{
+    0, 0, &cs_jsproxy,
+    { &critsect_debug.ProcessLocksList, &critsect_debug.ProcessLocksList },
+      0, 0, { (DWORD_PTR)(__FILE__ ": cs_jsproxy") }
+};
+static CRITICAL_SECTION cs_jsproxy = { &critsect_debug, -1, 0, 0, 0, 0 };
+
 /******************************************************************
  *      DllMain (jsproxy.@)
  */
@@ -46,3 +57,101 @@ BOOL WINAPI DllMain( HINSTANCE hinst, DWORD reason, LPVOID reserved )
     }
     return TRUE;
 }
+
+static inline void *heap_alloc( SIZE_T size )
+{
+    return HeapAlloc( GetProcessHeap(), 0, size );
+}
+
+static inline BOOL heap_free( LPVOID mem )
+{
+    return HeapFree( GetProcessHeap(), 0, mem );
+}
+
+static inline WCHAR *strdupAW( const char *src, DWORD len )
+{
+    WCHAR *dst = NULL;
+    if (src)
+    {
+        int dst_len = MultiByteToWideChar( CP_ACP, 0, src, len, NULL, 0 );
+        if ((dst = heap_alloc( (dst_len + 1) * sizeof(WCHAR) ))) len = MultiByteToWideChar( CP_ACP, 0, src, len, dst, dst_len );
+        dst[dst_len] = 0;
+    }
+    return dst;
+}
+
+static struct pac_script
+{
+    WCHAR *text;
+} pac_script;
+static struct pac_script *global_script = &pac_script;
+
+/******************************************************************
+ *      InternetDeInitializeAutoProxyDll (jsproxy.@)
+ */
+BOOL WINAPI InternetDeInitializeAutoProxyDll( LPSTR mime, DWORD reserved )
+{
+    TRACE( "%s, %u\n", debugstr_a(mime), reserved );
+
+    EnterCriticalSection( &cs_jsproxy );
+
+    heap_free( global_script->text );
+    global_script->text = NULL;
+
+    LeaveCriticalSection( &cs_jsproxy );
+    return TRUE;
+}
+
+static WCHAR *load_script( const char *filename )
+{
+    HANDLE handle;
+    DWORD size, bytes_read;
+    char *buffer;
+    int len;
+    WCHAR *script = NULL;
+
+    handle = CreateFileA( filename, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, 0 );
+    if (handle == INVALID_HANDLE_VALUE) return NULL;
+
+    size = GetFileSize( handle, NULL );
+    if (!(buffer = heap_alloc( size ))) goto done;
+    if (!ReadFile( handle, buffer, size, &bytes_read, NULL ) || bytes_read != size) goto done;
+
+    len = MultiByteToWideChar( CP_ACP, 0, buffer, size, NULL, 0 );
+    if (!(script = heap_alloc( (len + 1) * sizeof(WCHAR) ))) goto done;
+    MultiByteToWideChar( CP_ACP, 0, buffer, size, script, len );
+    script[len] = 0;
+
+done:
+    CloseHandle( handle );
+    heap_free( buffer );
+    return script;
+}
+
+/******************************************************************
+ *      InternetInitializeAutoProxyDll (jsproxy.@)
+ */
+BOOL WINAPI JSPROXY_InternetInitializeAutoProxyDll( DWORD version, LPSTR tmpfile, LPSTR mime,
+                                                    AutoProxyHelperFunctions *callbacks,
+                                                    LPAUTO_PROXY_SCRIPT_BUFFER buffer )
+{
+    BOOL ret = FALSE;
+
+    TRACE( "%u, %s, %s, %p, %p\n", version, debugstr_a(tmpfile), debugstr_a(mime), callbacks, buffer );
+
+    if (callbacks) FIXME( "callbacks not supported\n" );
+
+    EnterCriticalSection( &cs_jsproxy );
+
+    if (global_script->text)
+    {
+        LeaveCriticalSection( &cs_jsproxy );
+        return FALSE;
+    }
+    if (buffer && buffer->dwStructSize == sizeof(*buffer) && buffer->lpszScriptBuffer &&
+        (global_script->text = strdupAW( buffer->lpszScriptBuffer, buffer->dwScriptBufferSize ))) ret = TRUE;
+    else if ((global_script->text = load_script( tmpfile ))) ret = TRUE;
+
+    LeaveCriticalSection( &cs_jsproxy );
+    return ret;
+}