Wrong type check with undefined.

[malash]

In this line of code the typeof result could never return undefined so the condition will always be false.

      if (typeof result === undefined) {
        return result;
      }

The correct way to check if a value is undefined could be like typeof result === 'undefined' or result === 'undefined'.

BTW, A strict ESLint check is requested for an open source JavaScript project. The Airbnb one is a good choice.

[ihtml5]

Thank you for your suggestion. This is indeed a bug. I will fix it later. After being free, I will perfect eslint detection and unit testing

[ihtml5]

It has been fixed. This uses result === void 0 because undefined itself may be modified。