Global Vs Local

Scope determines the accessibility (visibility) of variables. Variables defined inside a function are not accessible (visible) from outside the function. In JavaScript we have two types of scope:

• Local scope
• Global scope

Local Scope:

Variables declared within a JavaScript function, become LOCAL to the function.  So, local variables have Function scope: They can only be accessed from within the function. Local variables are created when a function starts, and deleted when the function is completed.

Example: 
 // Here we can't use stud variable.
function myFunction() {
   var stud = "Adarsh";
  // Here we can use stud variable.
}

Also, since local variables are only recognized inside their functions, variables with the same name can be used in different functions.

Example: 
function myFunction1() {
   var stud = "Adarsh";
  // Rest Code.
}

function myFunction1() {
   var stud = "Vicky";
  // Rest Code.
}

Global Scope:

A variable declared outside a function, becomes GLOBAL. A global variable has global scope: All scripts and functions can access it. 

Example: 
var stud = "Adarsh";
 // Here we can use stud variable.
function myFunction() {
  // Here we can also use stud variable.
}

The lifetime of a JavaScript variable starts when it is declared. In a web browser, global variables are deleted when you close the browser window (or tab).

Note: If we assign a value to a variable that has not been declared, it will automatically become a GLOBAL variable. But now-a-days all modern browsers support running JavaScript in “Strict Mode”. In “Strict Mode”, undeclared variables are not automatically global.

Which of the follwing options is/are correct ?