[rodw]

I'm not sure this is the reason for that specific implementation but `Math.abs` _will_ do a string-to-number conversion.

I.e., `Math.abs("-27")` yields `27`.

It might be the case that Math.abs does other *-to-number conversions also, so maybe this method is trying to take advantage of that. (Math.abs is usually implemented as a native function so without digging more deeply it's not obvious to me what the actual implementation does.)

UPDATE: Curiously, `Math.abs(null)` yields `0`, so a null argument passed to is-even would yield `true` I guess.

Also whatever the logic is for that conversion is it is not the same as the built-in `parseInt` or `parseFloat`. `parseInt("27 meters")` yields `27` but `Math.abs("27 meters")` yields `NaN`.

Personally in JavaScript I almost universally make use of home-grown `isInt` and `toInt` methods whose behavior is predicable for me -- eg. my toInt() will reject a string that's not _just_ an integer value (and return `null` rather than `NaN` in all cases because who wants to check `isNaN`?) -- but that's probably not a great practice either. But I've been programming long enough to realize that the principle of least surprise is probably the most important concern here for long-term efficiency. I suppose what is or is not surprising may be subjective though.