var Hoisting in JavaScript

Question

This question already has answers here: question from:https://stackoverflow.com/questions/65874608/var-hoisting-in-javascript

Answer 1

When using var to declare variables, the variable can take on either function or global scope. If var is used within a function, it has function scope, if var is used outside of any function, the variable has Global scope.

So, your statement of:

But I also learnt that var has a global scope. Then var show not allow variable redeclaration.

Is actually, not really accurate because it depends on where var is used and redeclaration (more correctly known as variable "hiding") is possible in any smaller scope than the first declaration was made.

When declaring with var, the declaration is hoisted to the top of the scope.

I've written another answer that describes and demonstrates this in detail.