fixes 10697 [backport]

compiler/jsgen.nim

@@ -519,6 +519,7 @@ proc binaryUintExpr(p: PProc, n: PNode, r: var TCompRes, op: string,
     r.res = "$1 = (($5 $2 $3) $4)" % [a, rope op, y.rdLoc, trimmer, tmp]
   else:
     r.res = "(($1 $2 $3) $4)" % [x.rdLoc, rope op, y.rdLoc, trimmer]
+  r.kind = resExpr
 
 proc ternaryExpr(p: PProc, n: PNode, r: var TCompRes, magic, frmt: string) =
   var x, y, z: TCompRes
@@ -1912,13 +1913,13 @@ proc genMagic(p: PProc, n: PNode, r: var TCompRes) =
   of mHigh:
     unaryExpr(p, n, r, "", "($1 != null ? ($2.length-1) : -1)")
   of mInc:
-    if n[1].typ.skipTypes(abstractRange).kind in tyUInt .. tyUInt64:
+    if n[1].typ.skipTypes(abstractRange).kind in {tyUInt..tyUInt64}:
       binaryUintExpr(p, n, r, "+", true)
     else:
       if optOverflowCheck notin p.options: binaryExpr(p, n, r, "", "$1 += $2")
       else: binaryExpr(p, n, r, "addInt", "$1 = addInt($3, $2)")
   of ast.mDec:
-    if n[1].typ.skipTypes(abstractRange).kind in tyUInt .. tyUInt64:
+    if n[1].typ.skipTypes(abstractRange).kind in {tyUInt..tyUInt64}:
       binaryUintExpr(p, n, r, "-", true)
     else:
       if optOverflowCheck notin p.options: binaryExpr(p, n, r, "", "$1 -= $2")

tests/js/tbasics.nim

@@ -2,7 +2,8 @@ discard """
   output: '''ABCDC
 1
 14
-ok'''
+ok
+1'''
 """
 
 type
@@ -34,4 +35,14 @@ when true:
 
   a.setLen(0)
 
-  echo "ok"
+  echo "ok"
+
+# bug #10697
+proc test2 =
+  var val = uint16(0)
+  var i = 0
+  if i < 2:
+    val += uint16(1)
+  echo int(val)
+
+test2()