Answer: Var is function-scoped and can be redeclared or updated, while let and const are block-scoped. let allows reassignment, but const does not.

Answer: map() and filter() return new arrays, while forEach() doesn’t. map() transforms elements, and filter() selects elements based on a condition.

Answer: Arrow functions have a shorter syntax and don’t bind their own this, arguments, or super. They’re best for simple callbacks, while regular functions have their own this context.

Answer: JavaScript Promises handle asynchronous operations, representing a value that may be available now, later, or never. They have three states pending, fulfilled, and rejected managed using .then(), .catch(), and .finally().