JS Bin[Functions: Programs within progrms]// source https://jsbin.com/qotidus

jsbin.qotidus.js

//Functions//

/* Functions are like instructions that can be stored
* to use over and over again. They can be named, annonymous
* or assigned to a varible or constant. */

/* There are two phases of using functions. 
* 1. Declaring the function-- creating it
* 2. calling or invocation of the function to use it */

//Named function syntax (use keyword function)//
/* function name(parameter1, parameter2) {
*      function body (code to be executed)
* } 
* Named functions can be used by the program before they
* appear before it is sequentially appears because it is hoisted
* to the top of their scope.
*
*  Parmaeters are placeholders for the required input that
* needs to be passed into the function. You can set as many parameters
* needed for your function. The value being passed is called
* the arguement.
* To return a value use keyword return*/

function example(para1, para2) {
   return para1 + para2; 
}  //defined the function//

console.log(example(2,18)); //called the function. will return 20//
 
//Function Expression//
/* a fucntion is when an anonymous function is assigned
* to a varible or const */

var whatIf = function(num1,num2){
  if(num1 > num2) {
    return num1 + " is greater than";
  } else if(num1 < num2){
    return num2 + " is greater than";
  }else {
    return "Idk";
  }
};
console.log(whatIf(3,5)); // prints "5 is greater than"//

//Closures//

/* A closure is an inner function that has access to the outer function's
* variable scope chain.The closure has access to 3 scope chains. It can access
* it's own scope, it has access to the outer function's variables, and the global
* variables. */

function examples(artist) {
  var name = "My favorite artist is ";
  function examplesAgain() {
   return name + artist; 
  }
  return examplesAgain();
}
console.log(examples("Lloyd")); //prints "My favorite artist is LLoyd"//

// NOTE: Primitive (simple) values are passed to a function BY COPY, complex by reference. //
function tryingIt(string,string2) {
  return string + " " + string2;
}
console.log(tryingIt("I love R&b.", examples())); // "I love R&b. My favorite artist is Lloyd"