pureimpurefunc.js

//Pure and Impure function
//pure :
//Pure function is any function which has 2 features
//1. It should always return same output for same input
//2.It will never change/update the value of the global variable
//ex :
function prod(a, b) {
  return a * b; // This is a pure function
}
var ans1 = prod(1, 2);
var ans2 = prod(1, 2);
console.log(ans1, ans2);

// If any of two conditions are not maintain then impure function created
// Impure function :
//ex :
var x = 12;
function prod1(a, b) {
  var x = 15;
  return a * b; // although it gives same output, This is not a pure function
}
var ans1 = prod1(1, 2);
var ans2 = prod1(1, 2);
console.log(ans1, ans2);
//or
function out(a) {
  return Math.random() * a;
}
var res1 = out(2);
var res2 = out(2);
console.log(res1, res2);