Lesson 10! Global Var vs Local Var (2 variables)


#1

I am very confused when I see two Variables example

Var globalVar = "hello";

var foo = function() {
console.log(globalVar); // prints "hello"
}

why do we need "'var foo + function()" in this equation? I is really confusing me and I cant progress in java script because I dont understand!


#2

@perezwillz,

The keyword var is in =all-lower-case= ( you are using Var )

There are 2 ways to define a =FUNCTION=

  • the so-called named-function like function foo() { };
  • or via assigning a so-called anonymous-function to a variable
    like var foo = function() { };

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

In both cases you would have to call the =function=
like

foo();

#3

@perezwillz,

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".**


#4

@perezwillz,

### 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 ) );

#5

A post was split to a new topic: Local and Global variables