var and let create variables that can be reassigned another value.
const creates "constant" variables that cannot be reassigned another value.
if you're not going to change the value of a variable, it is good practice to use const.
After introduction of ES6 standard it is a good practise to avoid var.
To analyze the differences between these keywords, there are three factors:
1 - Scope of variables
Variables declared with var can have a global or local scope.
Global scope is for variables declared outside functions, while local scope is for
variables declared inside functions.
Variables declared with let and const can have a global, local, or block scope.
Block scope is for variables declared in a block. A block in JavaScript involves
opening and closing curly braces:
2 - Redeclaration and reassignment
Variables declared with var can be redeclared and reassigned.
Variables declared with let can be reassigned, but we cannot redeclare them.
Variables declared with const cannot be redeclared or reassigned.
3 - Hoisting
Variables declared with var are hoisted to the top of their global or local scope,
which makes them accessible before the line they are declared.
Variables declared with let are hoisted to the top of their global, local, or block scope,
but their hoisting is a little different from the one with var.
But, let and const variables are hoisted without a default initialization.
So when you try to access such variables, instead of getting undefined, or variable is
not defined error, you get cannot access variable before initialization.

This is my answer

Microsoft

The biggest difference is about the variable scope, so you should understand it first. Before you start explaining the difference, it is recommended t…