What is x in function(x)?


#1


I'm on "7. Search for a friend". For some time I had an error, and I found out what caused the error, but I don't understand why it doesn't work in the first place.

The first code doesn't work, but the second does. I can put anything into function(x) except for "friends". Why is that? In the previous exercise, when making a list, friends was acceptable inside "function(x)", but not in the search part. What's the difference?


    for (var x in friends) {
        if(friends[x].firstName === "Steve") {
            console.log(friends[x]);
            return friends[x];
        } else {
            console.log("No match!");
        }
    }
};

versus....

var search = function (name) {
    for (var x in friends) {
        if(friends[x].firstName === "Steve") {
            console.log(friends[x]);
            return friends[x];
        } else {
            console.log("No match!");
        }
    }
};



#2

@madipaolo2,

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

@madipaolo2,

var search = function (name) {
    //you have used =name= as PARAMETER
    // =name= PARAMETER is used as =local= VARIABLE
    for (var x in friends) {
        // here you reach out to the =global= VARIABLE =friends=
        // =friends= VARIABLE was defined OUTSIDE of the function-scope
        if(friends[x].firstName === name) {
            //here you wanted to compare the =firstName= PROPERTY-VALUE
            //with the =name= VARIABLE 
            console.log(friends[x]);
            return friends[x];
        }
        //imagine you would have a data-collection of 100 friends
        // you would get 60 "No match!" 
        //else {
        //    console.log("No match!");
        //}
    }
   //if you reach this line
   // you did not encounter the =return= statement
   // thus you would have not found any matching friends
   console.log("No match!");
};

Now if you call the search =function=
you will have to provide an argument
like
search("Steve")


#4

Beautiful. That was all extremely helpful. I feel like I understand functions a lot more now. The definitions of parameters and arguments finally clicked for me too. Thank you.


#5

@madipaolo2
Then also read
the discussion about 2 possible definition type's of a function

http://stackoverflow.com/questions/336859/var-functionname-function-vs-function-functionname?rq=1


#6

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