I have a question


#1

function getSubTotal(itemCount) {
return itemCount * 7.5;

what is the value of parameter itemCount ??


#2

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

the easy way to explain this is that the value of itemCount is whatever you put in parenthesis when calling the function. for example if you called the function like this: getSubTotal(7); then 7 would be the itemCount. in this exercise you are using another variable (orderCount) as the value instead of a number. so whatever the value of orderCount is will be the value of itemCount.

normally in functions the parameter in parenthesis is arbitrary. for example if you wrote a function like this:

var add = function(firstNumber, secondNumber) {
return firstNumber + secondNumber;
}
console log(add(3,4));

this way you can change the parameters (3 and 4 in my example) to whatever you want and the function will add them together. this is obviously a very simple example but it illustrates the way parameters are normally used in functions. its quite common to populate the parameter field with another variable. for example if you wanted to know how old you will be in a certain year:

var age = function(year) {
const birth = 1990;
return year - birth;
}
console.log(age(2017));

you can change the 2017 to any year to figure out how old you will be in that year. i hope this helps to explain it a little better. functions can be very complicated so its best to try and fully understand them using these simple exercises before trying to tackle the more complicated one.

reply or pm if you have any other questions and ill do my best to explain them.

MC


#4

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