13. Why is a function necessary?


#1


https://www.codecademy.com/en/courses/javascript-beginner-en-qDwp0/2/4?curriculum_id=506324b3a7dffd00020bf661


var programming = false;

var happy = function() {
  // Add your if/else statement here!
 if(programming ===!true) {
     return true
} else {
    return false};
};

Hello,

I figured out how to write the code but I don't understand the purpose of the [ var happy = function() { ]

why is this necessary? What purpose does it serve, and why can't you write this as just a regular if statement without creating a function variable?

ex.

var programming = false;

if(programming ===!true) {
return true
} else {
return false};
};


#2

@jrenai
They are trying to introduce the usage of a function

the FUNCTION talk

var myFunc = function( param1, param2) {
       //Begin of  anonymous FUNCTION-BODY
       //VARIABLE -myFunc- has an -anonymous function- assigned
       //this -anonymous function- has 2 PARAMETERS param1 and param2
       //param1 and param2 PARAMETERS are used 
       //as -local- VARIABLES throughout the FUNCTION-BODY

      console.log( param1 + " and " + param2 ) ;

      //End of anonymous FUNCTION-BODY
};

If you want to call/execute the anonymous function
you will have to add a pair of parentheses to the variable myFunc
like
myFunc();
As the anonymous function was defined
as having 2 parameters
you have to provide 2 arguments
in our case 2 string VALUES "Alena" and "Lauren"
like
myFunc("Alena","Lauren");

some quotes from the outer-world:

**argument is the value/variable/reference being passed in,
parameter is the receiving variable used within the function/block**

OR

**"parameters" are called "formal parameters",
while "arguments" are called "actual parameters".**

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

function with 1 parameter using return-statement

var myFunction = function( param1 ) {
       //Begin of FUNCTION-BODY
       //myFunction =function= has 1 PARAMETER param1
       //this param1 PARAMETER is used as a -local- VARIABLE
       //throughout the FUNCTION-BODY

      return param1;

      //End of FUNCTION-BODY
      };

you have defined a myFunction function
which takes 1 parameter param1
this param1 parameter is used
as a variable throughout the FUNCTION-BODY.

If you want to call/execute this myFunction function
and this myFunction function was defined
as having 1 parameter param1
you will have to provide 1 argument
in our case a "number VALUE" 4
myFunction( 4 );

some quotes from the outer-world:

**argument is the value/variable/reference being passed in,
parameter is the receiving variable used within the function/block**

OR

**"parameters" are called "formal parameters",
while "arguments" are called "actual parameters".**

============================================

As you are using the return-statement in your myFunction function
you will only get a return-value no-display.
You can however capture this return-value in a variable
and then use the console.log()-method to do a display.

var theResult = myFunction( 4 );
console.log( theResult );

OR directly

console.log( myFunction( 4 ) );

#3

How would we go about outputting a list of numbers in a program? Well there is the obvious,

console.log(1)
console.log(2)
console.log(3)
console.log(4)
console.log(5)
console.log(6)
console.log(7)
console.log(8)
console.log(9)

Another less repetitive way is in a loop...

for (var i = 1; i < 10; i++) {
    console.log(i);
}

Either way, this code only runs once. We see how the loop made console.log() non-repetive yet we could call it over and over? That is what re-usability is all about. To make our loop structure re-usable we wrap it in a function.

var countToNine = function () {
    for (var i = 1; i < 10; i++) {
        console.log(i);
    }
};
countToNine();

Now we can reproduce the list of numbers as often as we wish from anywhere in the program.


#4

Thank you both @mtf and @leonhard.wettengmx.n very helpful now I understand the purpose.