int64/uint64 as bigint in JS (#21613)

* int64/uint64 as bigint in JS

* fix CI

* convert to compile option

* fix lie

* smaller diff, changelog entry

1 files changed, 4 insertions, 3 deletions

diff --git a/tests/stdlib/tjson.nim b/tests/stdlib/tjson.nim
index a60d45aab..691bedeaa 100644
--- a/tests/stdlib/tjson.nim
+++ b/tests/stdlib/tjson.nim
@@ -1,6 +1,5 @@
 discard """
-  matrix: "--mm:refc"
-  targets: "c cpp js"
+  matrix: "--mm:refc; --backend:cpp --mm:refc; --backend:js --jsbigint64:off; --backend:js --jsbigint64:on"
 """
 
 
@@ -9,6 +8,7 @@ Note: Macro tests are in tests/stdlib/tjsonmacro.nim
 ]#
 
 import std/[json,parsejson,strutils]
+import std/private/jsutils
 from std/math import isNaN
 when not defined(js):
   import std/streams
@@ -314,7 +314,8 @@ block: # bug #17383
   else:
     testRoundtrip(int.high): "9223372036854775807"
     testRoundtrip(uint.high): "18446744073709551615"
-  when not defined(js):
+  whenJsNoBigInt64: discard
+  do:
     testRoundtrip(int64.high): "9223372036854775807"
     testRoundtrip(uint64.high): "18446744073709551615"