functions in javascript

 In javascript there are two type of functions 

1) function without any return value

function greet(name, greetText="Greetings from JavaScript"){
    let name1 = "Name1";
    console.log(greetText + " " + name);
    console.log(name + " is a good boy");
}

this function is called like 

let name = "Harry";
let name1 = "Shubham";
let name2 = "Rohan";
let name3 = "Sagar";
let greetText1 = "Good Morning";
greet(name, greetText1);
greet(name1, greetText1);
greet(name2, greetText1);

in this function if we didn't give a greet text value the default value we provide will be taken 

2) the function that gives a return value

function sum(a,b,c){
    let d = a + b + c;
    return d;
    // This line will never execute (Unreachable code)
    // console.log("Function is returned");
}

this function is called like 

let returnVal = sum(1,2,3);
console.log(returnVal)