Why is this an issue?
The == and != operators do type coercion before comparing values. This is bad because it can mask type errors. For
example, it evaluates ' \t\r\n' == 0 as true.
It is best to always use the side-effect-less === and !== operators instead.
Noncompliant code example
if (var == 'howdy') {...} // Noncompliant
Compliant solution
if (var === 'howdy') {...}
Exceptions
Even if testing the equality of a variable against null doesn’t do exactly what most JavaScript developers believe, usage of == or
!= is tolerated in such context. In the following case, if foo hasn’t been initialized, its default value is not
null but undefined. Nevertheless undefined == null, so JavaScript developers get the expected behavior.
if(foo == null) {...}
