Small and focused is good. Keeps from having to import a huge library (e.g., math.js) for simple functions when you don&#x27;t need what the rest of the library offers. Small surface.<p>Would <i>I</i> use is-even? No, I&#x27;d keep it in a local utility that bundles up other things my specific app needs, or package groups of small util libs into an app-specific uber-module.