JavaScript Let vs Var vs Constant : CodeCrafters.

In this video, we will discuss the differences between var, let, and const in JavaScript. It is important to understand these differences as variables play a crucial role in JavaScript coding, and using the correct variable type is essential for obtaining the desired output. We will explain the distinctions between var, let, and const with the help of examples.

var is a keyword traditionally used for variable declaration in JavaScript. However, in newer versions of JavaScript, let and const were introduced, and they are generally recommended over var. The primary difference between var and the other two lies in the scope in which the variable is accessible.

Let's take a look at an example using var:

We declare a variable x with a value of 10 using var.
Inside an if block, we declare another variable y with a value of 20 using var.
Both x and y are accessible within and outside the if block because var has function scope or global scope, meaning it is accessible throughout the entire function or globally.
Now, let's discuss let:

We declare a variable a with a value of 30 using let.
Inside an if block, we declare another variable b with a value of 40 using let.
a is accessible within and outside the if block, similar to var.
However, b is only accessible within the if block because let has block scope, meaning it is limited to the block of code where it is declared.
Lastly, we have const:

const is used to declare constants. Once a value is assigned to a const, it cannot be reassigned to a new value.
We declare a constant variable PI with a value of 3.14159.
PI cannot be reassigned a new value; any attempt to do so will result in an error.
In general, it is recommended to use let for variable declaration when you need to change the value over time, and const for constants that should not be modified. The use of var is generally limited to specific situations, such as working with legacy code or when you specifically need function scope or hoisting behavior.

I hope this explanation helps you understand the differences between var, let, and const in JavaScript. If you have any further questions, feel free to ask. Thank you for watching!