Coding Style

[sotayamashita]

What coding style are you using ?

If you have it, I recommend you create CONTRIBUTIG.md and write on it

[foray1010]

+1, there is no consistent coding style.

I suggest:

1. use const/let to replace all var, since this project had already using const.
2. use strict mode, to ensure others can import this library when they are using strict mode.
3. .eslintrc for us to check the coding style, I recommend the airbnb coding style.

[sotayamashita]

I suggest use standard instead of ESLint because it is very simple.