>Thankfully I wrote my own padStart function
This chimes with me as well. How often, in Python/Django you see an SO question that requires 20-30 lines of code.
With the recommendations to pip in package XYZ that does it for you. Now you have an external dependency for something super trivial.
JS should really tweak some basic stuff though. Even the humble sprintf seems missing. I use Handlebars for that now* but it's like swatting a fly with Yamato's 18"s.
* and mostly for templating