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 read the value of an undeclared variable (which you have to do before you can compare that value to the value of undefined) throws a ReferenceError.

Applying the typeof operator to an undeclared variable does not.