There's an argument to be made for writing functions like `isEven` and using them instead of n%2. There's an argument that the JS standard library, or other comprehensive util libraries like Lodash or Underscore should include these functions.
The problem here is introducing separate dependencies for each of these tiny functions. Dependencies are code that you haven't written, but are still your responsibility. For a lot of things, that's a good tradeoff: if you don't have the expertise in a specific area, or if you can offload work to a dependency that you trust, that's great. But for micro dependencies like this, it's usually a bad deal - you don't get anything in return (seriously, how hard is it to write your own isEven function?) but you have to rely on a third party to be secure, to not push anything accidentally broken, to not change the API, etc.
(I think it's also worth pointing out that your wife is not a paid programmer. Software development should be accessible, but this isn't the only goal, and I think it's reasonable to assume that most programmers either understand the n%2 idiom, or know enough to be able to find help on the subject.)
The problem here is introducing separate dependencies for each of these tiny functions. Dependencies are code that you haven't written, but are still your responsibility. For a lot of things, that's a good tradeoff: if you don't have the expertise in a specific area, or if you can offload work to a dependency that you trust, that's great. But for micro dependencies like this, it's usually a bad deal - you don't get anything in return (seriously, how hard is it to write your own isEven function?) but you have to rely on a third party to be secure, to not push anything accidentally broken, to not change the API, etc.
(I think it's also worth pointing out that your wife is not a paid programmer. Software development should be accessible, but this isn't the only goal, and I think it's reasonable to assume that most programmers either understand the n%2 idiom, or know enough to be able to find help on the subject.)