code: function(stack) {
      var url, matches;
      if (typeof stack === "string" && stack) {
        matches = stack.match(/^(?:|[^:@]*@|.+\)@(?=http[s]?|file)|.+?\s+(?: at |@)(?:[^:\(]+ )*[\(]?)((?:http[s]?|file):\/\/[\/]?.+?\/[^:\)]*?)(?::\d+)(?::\d+)?/);
        if (matches && matches[1]) {
          url = matches[1];
        } else {
          matches = stack.match(/\)@((?:http[s]?|file):\/\/[\/]?.+?\/[^:\)]*?)(?::\d+)(?::\d+)?/);
          if (matches && matches[1]) {
            url = matches[1];
          }
        }
      }
      return url;
    }
docs: Get the current script's URL by throwing an `Error` and analyzing it.
  
  @returns String or `undefined`
  @private