fix #8821 (#15809)

1 files changed, 5 insertions, 0 deletions

diff --git a/compiler/jsgen.nim b/compiler/jsgen.nim
index cd14f1cf9..10c072253 100644
--- a/compiler/jsgen.nim
+++ b/compiler/jsgen.nim
@@ -865,6 +865,7 @@ proc genRaiseStmt(p: PProc, n: PNode) =
 proc genCaseJS(p: PProc, n: PNode, r: var TCompRes) =
   var
     cond, stmt: TCompRes
+    totalRange = 0
   genLineDir(p, n)
   gen(p, n[0], cond)
   let stringSwitch = skipTypes(n[0].typ, abstractVar).kind == tyString
@@ -884,6 +885,10 @@ proc genCaseJS(p: PProc, n: PNode, r: var TCompRes) =
         let e = it[j]
         if e.kind == nkRange:
           var v = copyNode(e[0])
+          inc(totalRange, int(e[1].intVal - v.intVal))
+          if totalRange > 65535:
+            localError(p.config, n.info, 
+                       "Your case statement contains too many branches, consider using if/else instead!")
           while v.intVal <= e[1].intVal:
             gen(p, v, cond)
             lineF(p, "case $1:$n", [cond.rdLoc])