Uncaught exceptions in JS now always propagate with better stack trace.

lib/system/jssys.nim

@@ -7,11 +7,6 @@
 #    distribution, for details about the copyright.
 #
 
-when defined(nodejs):
-  proc alert*(s: cstring) {.importc: "console.log", nodecl.}
-else:
-  proc alert*(s: cstring) {.importc, nodecl.}
-
 proc log*(s: cstring) {.importc: "console.log", varargs, nodecl.}
 
 type
@@ -101,9 +96,6 @@ proc getStackTrace*(): string = rawWriteStackTrace()
 
 proc unhandledException(e: ref Exception) {.
     compilerproc, asmNoStackFrame.} =
-  when NimStackTrace:
-    var buf = rawWriteStackTrace()
-  else:
   var buf = ""
   if e.msg != nil and e.msg[0] != '\0':
     add(buf, "Error: unhandled exception: ")
@@ -113,12 +105,21 @@ proc unhandledException(e: ref Exception) {.
   add(buf, " [")
   add(buf, e.name)
   add(buf, "]\n")
-    alert(buf)
+  when NimStackTrace:
+    add(buf, rawWriteStackTrace())
+  let cbuf : cstring = buf
+  {.emit: """
+  if (typeof(Error) !== "undefined") {
+    throw new Error(`cbuf`);
+  }
+  else {
+    throw `cbuf`;
+  }
+  """.}
 
 proc raiseException(e: ref Exception, ename: cstring) {.
     compilerproc, asmNoStackFrame.} =
   e.name = ename
-  when not defined(noUnhandledHandler):
   if excHandler == 0:
     unhandledException(e)
   when defined(nimphp):
@@ -130,7 +131,6 @@ proc reraiseException() {.compilerproc, asmNoStackFrame.} =
   if lastJSError == nil:
     raise newException(ReraiseError, "no exception to reraise")
   else:
-    when not defined(noUnhandledHandler):
     if excHandler == 0:
       var isNimException: bool
       when defined(nimphp):
@@ -139,6 +139,7 @@ proc reraiseException() {.compilerproc, asmNoStackFrame.} =
         asm "`isNimException` = lastJSError.m_type;"
       if isNimException:
         unhandledException(cast[ref Exception](lastJSError))
+
     asm "throw lastJSError;"
 
 proc raiseOverflow {.exportc: "raiseOverflow", noreturn.} =
@@ -873,3 +874,10 @@ proc nimParseBiggestFloat(s: string, number: var BiggestFloat, start = 0): int {
   # evaluate sign
   number = number * sign
   result = i - start
+
+when defined(nodejs):
+  # Deprecated. Use `alert` defined in dom.nim
+  proc alert*(s: cstring) {.importc: "console.log", nodecl, deprecated.}
+else:
+  # Deprecated. Use `alert` defined in dom.nim
+  proc alert*(s: cstring) {.importc, nodecl, deprecated.}

web/news/version_0_15_released.rst

@@ -57,6 +57,9 @@ that have tuple name:
 - Now when you compile console application for Windows, console output
   encoding is automatically set to UTF-8.
 
+- Unhandled exceptions in JavaScript are now thrown regardless ``noUnhandledHandler``
+  is defined. But now they do their best to provide a readable stack trace.
+
 Library Additions
 -----------------