1 files changed, 6 insertions, 0 deletions
diff --git a/lib/js/jsffi.nim b/lib/js/jsffi.nim
index e1c59803d..7f0939b08 100644
--- a/lib/js/jsffi.nim
+++ b/lib/js/jsffi.nim
@@ -104,6 +104,12 @@ var
   jsFilename* {.importc: "__filename", nodecl.}: cstring
     ## JavaScript's __filename pseudo-variable
 
+proc isNull*[T](x: T): bool {.noSideEffect, importcpp: "(# === null)".}
+  ## check if a value is exactly null
+
+proc isUndefined*[T](x: T): bool {.noSideEffect, importcpp: "(# === undefined)".}
+  ## check if a value is exactly undefined
+
 # Exceptions
 type
   JsError* {.importc: "Error".} = object of JsRoot