When do functions have no limit?

Question

When do functions have no limit?

Answer 1

Functions have no limit when their limit is not defined or does not exist, such as

lim x-> ∞ sin(x)

lim x-> ∞ cos(x)

Answer 2

when x-->a for some function

and when x-->a+ is not same as x-->a- for that function thats when the limit doesnt exist even if it's at infinity