What is scope in Javascript
Scope in JavaScript refers to the accessibility or visibility of variables and expressions. That means the space where an item, such as a variable or a function, is visible and accessible in your code.
For example, once a variable is declared, it can only be accessible within the scope that it has been declared in and will not be accessible outside the scope.
JavaScript has 3 types of scope:
Global scope Block scope/Function scope Local scope
Global Scope
Variables and functions declared in the global scope are accessible from anywhere in your JavaScript code, both within and outside of functions.
Global variables are declared outside of any function, typically at the top level of a JavaScript file or within a script tag in an HTML document.
Functions declared in the global scope are also accessible from anywhere.
let Name = "Kaushal";
// code here can use Name
function myFunction() {
// code here can also use Name
}
Block scope
The scope created with a pair of curly braces (a block).
A function creates a scope, so that (for example) a variable defined exclusively within the function cannot be accessed from outside the function or within other functions. For instance, the following is invalid:
function exampleFunction() {
const x = "declared inside function"; // x can only be used in exampleFunction
console.log("Inside function");
console.log(x);
}
console.log(x); // Causes error
const x = "declared outside function";
exampleFunction();
function exampleFunction() {
console.log("Inside function");
console.log(x);
}
console.log("Outside function");
console.log(x);
Local Scope
Variables declared within a function are only accessible from within that function. This is known as function scope. Function scope helps to prevent variables from conflicting with each other and makes your code more modular and reusable.
// code here can NOT use Name
function myFunction() {
let Name = "Kaushal";
// code here CAN use Name
}
// code here can NOT use Name
