- *`var`:*
- Function-scoped.
- Hoisted and initialized with `undefined`.
- Can be re-declared within the same scope without an error.
- *`let`:*
- Block-scoped.
- Hoisted but not initialized (temporal dead zone).
- Cannot be re-declared within the same scope.
For most scenarios, it's preferable to use `let` due to its block-scoping and more predictable behavior.
Certainly:
- *`var`:*
- Function-scoped, not block-scoped.
- Hoisted to the top of its function or global scope.
- Allows re-declaration within the same scope.
- Can be accessed before the declaration (due to hoisting) with an initial value of `undefined`.
- *`let`:*
- Block-scoped, meaning it's limited to the block where it's defined.
- Hoisted to the top of its block, but not initialized (results in a temporal dead zone).
- Does not allow re-declaration within the same scope.
- Provides more predictable scoping behavior, especially in loops and conditional statements.
In modern JavaScript, `let` is often preferred over `var` for its block-scoping and improved handling of variable declarations.