JavaScript Variable Scope - JavaScript Tutorial 63

Pubblicato il: 05 settembre 2017
sul canale di: ChidresTechTutorials

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Notes for You:: JavaScript Variable Scope - JavaScript Tutorial 63
Local scope Vs Global scope in JavaScript.
Scope indicates the accessibility and visibility of variables.
JavaScript variables are of local scope (function scope) or global scope

Local scope:
Any variable declared inside a function is considered as in local scope
can be accessible only inside that function where it is declared
Local variables will be available only in the function execution
Local variables are created as soon as the control enters the function body and deleted as soon as the control exits the function body.

Global scope:
Any variable not declared inside a function is considered as in global scope
can be accessible anywhere in the script
Global variables will be available throughout the script execution

Example Code 1:
var a=10;
document.write("a= ", a, " "); // 10
function display(){
document.write("a= ", a," "); // 10
var b=20;
document.write("b= ", b," "); // 20
}
display();
document.write("b= ", b," "); // error: b is not defined

Example Code 2:
var a=10;
document.write("a= ", a, " "); // 10
var b=30;
function display(){
document.write("a= ", a," "); // 10
var b=20;
document.write("b= ", b," "); // 20
}
display();
document.write("b= ", b," ");//30

Note:
replace < with less-than symbol.
replace > with greater-than symbol.

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JavaScript Tutorial 64 - Functions Vs. Call Stack in JavaScript
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