JavaScript tips

Shorthand

Boolean(0)	!!0
String(3.14)	3.14 + ""
Number("3.14")	+ "3.14"
Math.floor(3.14)	~~3.14 or 3.14 << 0
undefined	void 0
10000	1e4

flatMap

result = []
for (v of array)
  if (v !== 0)
    array.push(1/v)

• array.map(v => v !== 0 && 1/v).filter(v => v)
• array.flatMap(v => v === 0? []: 1/v)

Math

const {sin, asin} = Math
[0, 1, 2].map(sin).map(asin)

template literal

function upper(args) {
  return args[0].toUpperCase()
}
const text = upper`hi` // HI

functional object

const hello = () => 'HELLO'
hello.world = () => 'WORLD'
hello()           // HELLO
hello.world()     // WORLD

assignment

let t = -1,
   dt = 100 - (~t? t: (t = 0))
console.log(t) // 0