JavaScript Functions

function add(num1, num2) {
  return num1 + num2;
}

// The parameter is name
function sayHello(name) {
  return `Hello, ${name}!`;
}

const dog = function() {
  return 'Woof!';
}

// Defining the function
function sum(num1, num2) {
  return num1 + num2;
}
// Calling the function
sum(2, 4); // 6

// With return
function sum(num1, num2) {
  return num1 + num2;
}
// The function doesn't output the sum
function sum(num1, num2) {
  num1 + num2;
}

#With two arguments

const sum = (param1, param2) => { 
  return param1 + param2; 
}; 
console.log(sum(2,5)); // => 7 

#With no arguments

const printHello = () => { 
  console.log('hello'); 
}; 
printHello(); // => hello

#With a single argument

const checkWeight = weight => { 
  console.log(`Weight : ${weight}`); 
}; 
checkWeight(25); // => Weight : 25 

#Concise arrow functions

const multiply = (a, b) => a * b; 
// => 60 
console.log(multiply(2, 30)); 

Arrow function available starting ES2015

// Named function
function rocketToMars() {
  return 'BOOM!';
}
// Anonymous function
const rocketToMars = function() {
  return 'BOOM!';
}

// Defining the function:
function sum(num1, num2) {
  return num1 + num2;
}
// Calling the function:
sum(3, 6); // 9