Functions in JavaScript.

1. Introduction
Function is a block of code which perform specific task in a better and efficient way.

Syntax
It is defined using function keyword, then followed by the name of the function say var1, followed with parentheses ().
Function name follows same rules as of variable name.

function var1(par1, par2) {
code to be executed
}

2. Uses of Functions
Functions basically resist the repetition of same code again and again. Once the code is designed, we can use it multiple times just by giving the
arguments.

Example:

function add(num1, num2) {
  const addition = num1 + num2;
  console.log(addition);
}
add(2, 1);
add(63,232):

Output:
3
295
3. Function Return
When return keyword is used in Function and it reaches to return statement, the code will stop executing. Return keyword helps in future use of the output of Function.

For example:

function multi(par1, par2) {
  return par1 * par2;
}
console.log(multi(10, 2));