jonrandy

const fib = n => {
  const r5 = fib.r5 || (fib.r5=5**.5)
  return Math.floor((((1+r5)/2)**n - ((1-r5)/2)**n)/r5)
}

jonrandy

const isPalindrome = ([...s]) => ''+s == s.reverse()

jonrandy

function fibonacci(n) {
	if (n < 0) throw RangeError("Negative arguments not implemented")
	return fib(n)[0]
}

function fib(n) {
	if (n) {
		const [a, b] = fib(~~(n / 2)),
		  c = a * (b * 2n - a),
		  d = a * a + b * b

jonrandy

Every programmer occasionally, when nobody’s home, turns off the lights, pours a glass of scotch, puts on some light German electronica, and opens up a file on their computer. It’s a different file for every programmer. Sometimes they wrote it, sometimes they found it and knew they had to save it. They read over the lines, and weep at their beauty, then the tears turn bitter as they remember the rest of the files and the inevitable collapse of all that is good and true in the world.

This file is Good Code. It has sensible and consistent names for functions and variables. It’s concise. It doesn’t do anything obviously stupid. It has never had to live in the wild, or answer to a sales team. It does exactly one, mundane, specific thing, and it does it well. It was written by a single person, and never touched by another. It reads like poetry written by someone over thirty.

Every programmer starts out writing some perfect little snowflake like this. Then they’re told on Friday they need to have six hundred snow

jonrandy

const fizzBuzz = x=>[x,f='Fizz',b='Buzz',f+b][!(x%5)*2+!(x%3)]

const fizzBuzz = (x,f='Fizz',b='Buzz')=>[x,f,b,f+b][!(x%5)*2+!(x%3)]

const fizzBuzz = x=>({1:x,6:f="Fizz",10:b="Buzz",0:f+b}[x**4%15])

const fizzBuzz = (x,f="Fizz",b="Buzz")=>({1:x,6:f,10:b,0:f+b}[x**4%15])

jonrandy

const isPrime = x=>!'1'.repeat(x).match(/^1?$|^(11+?)\1+$/)

jonrandy

const isValidCSSColour = str => {
  const s = new Option().style
  s.color = str
  return s.color != ''
}

jonrandy

jonrandy

Number.prototype[Symbol.iterator] = function* () {
  for (let i = 1; i <= this; i++) yield i
}

[...5] // [1,2,3,4,5]

jonrandy

const getFlagEmoji = countryCode=>String.fromCodePoint(...[...countryCode.toUpperCase()].map(x=>0x1f1a5+x.charCodeAt(0)))