A fairly recent addition to Typescript is index types and the keyof operator.

ECMAScript is all about wrangling loosely typed variables.

When learning a language built on another existing platform, like TypeScript (or, for that matter Kotlin), one of the challenges you face is understanding the underlying platform or language so that you can, in turn, understand how the higher-level language is applied to meet the restrictions and features of the lower-level language.

Kotlin has an annotation called @JvmDefault which, like most of the “Jvm” prefixed annotations, exists to help massage the Kotlin compiler output to match Java classes in a certain way. This annotation was added in 1.2.40, and has now seen some experimental enhancements in 1.2.50, so it seems worth exploring what this is all about.

Recently, I was driving my 2015 Jeep Wrangler JK Unlimited through a parking lot on a 95 degree day, and after leaving a stop sign, a check engine light flashed on (later I would learn it was a P0480 Cooling Fan Relay 1 Control Circuit), and shortly thereafter my Jeep overheated. What followed was a multi-day Google searching and diagnostic session, which made me realize there is a lack of information as well as a lot of mis-information about the 3.6L “Pentastar” Jeep Wrangler model years, and how the radiator fan works.

This is my summary of what I learned about the cooling fans on these Jeeps, so hopefully more people can diagnose issues themselves.