49.Pure_Function.js

//What is pure function?

// It returns the same result if given the same arguments
// It dose not cause any observable side effects

// pure function
function sqr(n){
  return n*n
}

console.log(sqr(2))
console.log(sqr(2))
console.log(sqr(2))

// not a pure function

var n = 10

function change(){
  n = 100
}
change()
console.log(n)

var point = {
  x: 45,
  y: 30
}
function printPoint(point){
  point.x = 100
  point.y = 200
  console.log(point)
}
console.log(point)
printPoint(point)
console.log(point)