5 differences between var, let and const in JavaScript

1.????? Scope

·?????? Var : This is a function scope, and it is accessible within the function, regardless of the block boundaries. For example, inside if, for.

·?????? Let: This is a blocked-scope, and it is only accessible within the block {} in which it’s defined.

·?????? Const: Blocked-Scoped, like let, but also ensures the variable is read-only after assignment.

2.????? Re-declaration

Var: This can be re-declared within the same scope without error.

let: This cannot the re-declared within the same scope.

const: ?it cannot be re-declared within the same scope, similar to let.

3.????? Initialization

·?????? Var: Variables declared with var are initialized as undefined during hoisting.

·?????? Let: Variables declared with let ?are not initialized until their declarations is evaluated.

·?????? Const: it must be initialized during declarations, otherwise, an error is thrown

4..????? Hoisting

·?????? Var: Variables declared with var are hoisted to the top of their scope and initiated with undefined.

·?????? let: Variables are hoisted but are not initialized, leading to a “Temporal Dead Zone”(TDZ) until their declaration.

·?????? const: This is similar to let, const is hoisted but not initialized, and also has a TDZ.

5. ????? Re-assignment

·?????? Var: This can be re-assigned.

?·?????? Let: This is be re-assigned.

·?????? Const: This can not be re-assigned. Once it is assigned, the value cannot change.