How To Debug js code in the board?

old topic...
I'm trying to put debugger; into code. but emulator does not stop there.

var myMenu = {
    "" : { 
      "title" : "Title"
    },
    "< Back" : () => back(),
    "Test": {
      value:"X",
      format : function (v) {
        debugger;
        var options=myMenu[""];
        var fh = options.fontHeight;
        print(myMenu);
        return v;
      }
    },
  };
E.showMenu(myMenu);