No, please no. If size is an issue for some reason or you want to have no dependencies you can use something like http://zeptojs.com/ and just embed everything in one minified file. If you do things right only the functions you are actually using will get placed in there as well.

Do not reinvent the wheel to solve problems that can't be solved in much cleaner and nicer ways. Managing dependencies can be annoying, but we all bite the bullet for a very good reason, because reusing solid well tested code is a good thing.

  For example, in eastern Wyoming, an analysis showed that 
  it would cost half a million dollars to construct a water 
  well into deep, but high-quality aquifer reserves. That, 
  plus an untested assumption that all the deep layers 
  below it could only contain poor-quality water, led 
  regulators to allow a uranium mine to inject more than 
  200,000 gallons of toxic and radioactive waste every day 
  into the underground reservoirs.

WHAT THE FUCK

Man, that video, typical marketing bullshit. First scene shows a guy writing on a typewriter, next scene shows someone hanging up Polaroid pictures. Seriously? Show me why this app is useful and why I need it, instead of trying to lull me into a world that doesn't exist.