Understand Referential transparency with example

referential_transparency.js

let a = (num1,num2) => {
  return num1+num2;
}

let b = (num) => {
  return num*2;
}

console.log(b(a(3,4))) //output will be 14
// here i can replace a(3,4) expression with value 7 value and this will not effect to the result of the program because its return
// value is 7
// so i can replace  console.log(b(a(3,4))) to console.log(b(7)) as a function is refrencially transparent

let c = (num1,num2) => {
  console.log(`Value of num1:${num1} and value of num2:${num2}`);
  return num1+num2;
}

console.log(b(c(3,4))) //output will be 14
// here i cannot replace expression c(3,4) with value 7 as it effect the result of the program
// function c has console.log() which is one type of side effect so it is not referentially transparent