| Scope |
Function scope; variable is accessible inside function even if declared after usage |
Block scope; variable is only accessible inside nearest enclosing {…} |
Block scope; variable is only accessible inside nearest enclosing {…} |
| Re-declared |
Can re-declare var anywhere in the function |
Cannot re-declare let in the same block |
Cannot re-declare const anywhere |
| Updated |
Can update/reassign the value |
Can update/reassign the value |
Cannot update/reassign the value, must be initialized and value cannot change |
| Hoisted |
Function scoped variables are hoisted to the top of the function |
hoisted to the top of its block or scope, but it is not initialized. Accessing the variable before its declaration results in a ReferenceError. |
hoisted to the top of its block or scope, but it is not initialized. Accessing the variable before its declaration results in a ReferenceError. |