What is the difference between var, let and const?

In JavaScript, var, let, and const are all used to declare variables. Each of these keywords has its specific meaning and behaviour, and they should be used in different situations depending on the requirements of your code.

The main differences between var, let, and const are as follows:

• var is the traditional way of declaring variables in JavaScript. It is function-scoped, which means that a var variable is only accessible within the function in which it is declared. var variables can be reassigned and redeclared within their scope.
• let is a newer way of declaring variables in JavaScript. It is block-scoped, which means that a let variable is only accessible within the block (such as a for loop or a if statement) in which it is declared. let variables can be reassigned, but they cannot be redeclared within their scope.
• const is also a newer way of declaring variables in JavaScript. It is block-scoped, just like let. const variables must be assigned a value when declared, and they cannot be reassigned or redeclared within their scope. This makes const variables read-only.

In general, it is recommended to use const whenever possible and only use let if you need to reassign the value of a variable. var should be avoided unless you are working with older code that uses var extensively. Using const and let helps to make your code more readable and maintainable, and it can also prevent common mistakes and bugs.