BC2

//Writing reusable code with functions
function ourReusableFunctionName() { //may pass info to (). Function is also being defined as ourReusableFunctionName
    console.log("Hi, World"); //Info inside this curly bracket is run when the function is called
}

ourReusableFunctionName(); //function is being called here

/*Passing values to functions with arguments

Parameters are variables that act as placeholders for values that are to be input to a function
when it's called.*/

function ourFunctionwithArgs(a, b) {
    console.log(a - b);
}
ourFunctionwithArgs(10, 5) //when this function is called, data (10, 5) is passed into the function


/*Global scope and functions
Scope refers to the visibility of variables. These variables are defined/anywhere outside of a
function block have global scope.

Global scope refers to them being seen anywhere in JS code.*/
var myGlobal = 10; //this is a global scope, outside a function
function fun1() {
    oopsGlobal = 5; /*this is a GLOBAL Function in a function for NOT having var.
    Var oopsGlobal = 5, This is scoped WITHIN function, aka LOCAL scope*/
}

function fun2() {
    var output = "";
    if (typeof myGlobal != undefined ) {
        output += "myGlobal: " + myGlobal;
    }
    if (typeof oopsGlobal != undefined) {
        output += " oopsGlobal: " + oopsGlobal //undefined would show if it was var oopsGlobal
    }
    console.log(output);
}

fun1();
fun2();

//Local scope and functions

function theLocalScope() { /*variables declared within a function/function parameters have LOCAL scope.
                           meaning that they are visible within the function.*/

    var myVar = 20   //this variable is declared within the function, hence only visible there.
    console.log(myVar);
}
theLocalScope();

/*console.log(myVar); This doesn't work since it tried to access myVar outside the function*/


//Global vs. Local Scope in Functions
//It's possible to both have GLOBAL and LOCAL variables with the same name.
//The LOCAL variable takes precedence over the global variable
var outerWear = "T-shirt";

function myOutfit() {
    var outerWear = "Sweater" //This would appear instead of T-shirt.

    return outerWear;
}

console.log(myOutfit());
console.log(outerWear) //T-shirt appears here, since it's logging GLOBAL variable.


//Returing values from a Function with Return
function minusSeven(num) {
    return num -7; //This gives back the result from 10-7
}

console.log(minusSeven(10))

//Understanding Undefined Value Returned from a function