Using typeof vs === to check undeclared variable produces different result

Question

If I have an undeclared variable and use typeof it tells me it\'s undefined. But if I then check it using if (qweasdasd === undefined)

Answer 1

Trying to access undefined variable in Javascript gives ReferenceError. typeof is working because it not accessing variable value. Its checking its type.

typeof not requires defined variable. Its parameter should be an expression representing the object or primitive whose type is to be returned.