eqeqeq
Enforces the use of type-safe equality operators === and !== instead of the
more error prone == and != operators.
=== and !== ensure the comparators are of the same type as well as the same
value. On the other hand == and != do type coercion before value checking
which can lead to unexpected results. For example 5 == "5" is true, while
5 === "5" is false.
Invalid:
if (a == 5) {}
if ("hello world" != input) {}
Valid:
if (a === 5) {}
if ("hello world" !== input) {}