fixes #6753

tests/js/test2.nim

@@ -2,7 +2,9 @@ discard """
   output: '''foo
 js 3.14
 7
-1'''
+1
+-21550
+-21550'''
 """
 
 # This file tests the JavaScript generator
@@ -40,3 +42,14 @@ procThatRefersToConst() # Call bar before it is defined
 proc procThatRefersToConst() =
   var i = 0 # Use a var index, otherwise nim will constfold foo[0]
   echo someConst[i] # JS exception here: foo is still not initialized (undefined)
+
+# bug #6753
+let x = -1861876800
+const y = 86400
+echo (x - (y - 1)) div y # Now gives `-21550`
+
+proc foo09() =
+    let x = -1861876800
+    const y = 86400
+    echo (x - (y - 1)) div y # Still gives `-21551`
+foo09()