Scope of Variables in JavaScript

Scope determines the accessibility (visibility) of variables.

In JavaScript there are two types of scope:

  • Local scope
  • Global scope

JavaScript has function scope: Each function creates a new scope. Scope determines the accessibility (visibility) of these variables. Variables defined inside a function are not accessible (visible) from outside the function.

Local JavaScript Variables

Variables declared within a JavaScript function, become LOCAL to the function. Local variables have Function scope: They can only be accessed from within the function.  Since local variables are only recognized inside their functions, variables with the same name can be used in different functions. Local variables are created when a function starts, and deleted when the function is completed.

Example –

Global JavaScript Variables

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

Example –

 

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