In this lesson, we will explore how to declare variables in JavaScript using let and const. Understanding these keywords is crucial for writing clean and effective code in JavaScript. 

Definition: 

• let allows users to declare variables that are limited in scope to the block, statement, or expression where they are used.
• const  enables the declaration of variables meant to remain constant or unchanged through the script. A const declaration creates a variable that cannot be reassigned after its initialization and shares the block-scoped nature of let.

Examples:

• Variable declaration with let.

let x = 100;

In this example, x is declared with let and initialized with the value 100. x can be reassigned within its scope.

• Variable declaration with const

const y = 150;

Here, y is declared with const and set to 150. Unlike let, y cannot be reassigned to a new value.

Outputs: 

• if you run console.log(x) and console.log(y) are 100 and 150, respectively.

❗Note: It is important to understand that while let allows reassignment, any const variable does not. Attempting to reassign a const variable will result in a TypeError.

let x = 100;
x = 200;  // This is allowed
const y = 150;
y = 200;  // This will throw a TypeError: Assignment to constant variable.