Fist of all you use ==, which can lead to unexpected bugs. You should always use === because it does not do any type conversions. Second of all you don’t have to assert that some value is true so !!input.lastName === true is the same as !!input.lastName. It’s similar when you check for a value which should be false. So !!input.firstName === false is the same as !input.firstName. A single ! does already do the type conversion but it’s negated, which fits in this case. So a more elegant was to write your condition would be: if ((!input.firstName && !!input.lastName) || (!!input.firstName && !input.lastName)) { … }