Developed a library in node.js for battery information in Windows OS a month ago.

https://github.com/0xsuid/...

Give your valuable suggestion / opinions.

Looks fine to me. I would suggest using camel case for your variabable names e.g. isCharging instead of ischarging and use less abbreviations e.g. currentCapacity instead of currcap. The few extra keystrokes (if any thanks to autocomplete) are worth the reduced cognitive load. Also maybe add a few tests to it?

@musician thanks for suggestion, I will fix those things and add tests to it.