docs: private static String js_concat(String target, Object[] args) {
          int N = args.length;
          if (N == 0) { return target; }
          else if (N == 1) {
              String arg = ScriptRuntime.toString(args[0]);
              return target.concat(arg);
          }
  
          // Find total capacity for the final string to avoid unnecessary
          // re-allocations in StringBuilder
          int size = target.length();
          String[] argsAsStrings = new String[N];
          for (int i = 0; i != N; ++i) {
              String s = ScriptRuntime.toString(args[i]);
              argsAsStrings[i] = s;
              size += s.length();
          }
  
          StringBuilder result = new StringBuilder(size);
          result.append(target);
          for (int i = 0; i != N; ++i) {
              result.append(argsAsStrings[i]);
          }
          return result.toString();
      }