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