"Big integers" have landed in Javascript, at least in Firefox and Chrome. One of interesting things to do with high precision arithmetic is to calculate digits of π. From scratch, that is, using only addition, subtraction, multiplication, and division.
If the React docs leave you in the dust, or Dan Abramov's blog makes you feel like you're reading a scroll handed down from Mt Olympus written in ancient Greek, you're not alone…
You won't see new elements added to the head element because the parsing algorithm only allows for title, meta, style, script, base and link. Today, if your browser spots anything else in the <head> tag, it'll land in the body element in the DOM.
Keeping time in JavaScript is kind of a joke, not just because time is a social construct, but because it’s really easy to write code that blocks the timekeeper. Remember: JavaScript inherently only has one thread, which it uses for everything.