Echo JS 0.11.0

reads a bit like a sales pitch
"now with blockchain"

The regular expression part of this is rather small.
Most of the article talks about mapping the fields to US states, cities and zipcodes.
Question is: do you want to maintain those yourself ? (and load them all client side ;-))

Alternatively one could use:
https://developers.google.com/maps/documentation/javascript/places-autocomplete

or if you only need the US:
https://www.ups.com/us/en/services/technology-integration/us-address-validation.page

and there are probably many more ;-)

Paywalled

Not Javascript related

Bonus point for click-bait title.
Personally Clojurescript reminds me of Lisp.

A key value store in memory adds little value imho, we already have native objects which are hard to beat performance wise. 

Persistence is another ballgame. Every now and then people need persistence, there you might be able to add value.
Having said that: that space is already quite full (e.g. think pouchDB, levelDB, lokijs ) so you will need to find a niche which you serve better than the rest.

Good luck !

I'm pretty sure the Arduino example works, as it looks quite similar to Arduino code. Now what would be interesting is if the hello world example would compile for Arduino (eg. Console.log being handled by a serial.write)

I'm a bit sceptical. 


http://enclosejs.com explains some of the challenges in compiling JavaScript.

Also on the smaller platforms like Arduino do have http://www.espruino.com but are quite limited in memory size so you really need to know what you are doing.

A discussion on the subject can be found at:

https://news.ycombinator.com/item?id=13287002

The boolean trick works but as you can see there is still a lot of repetitive code in your example.

A simple function (e.g. getProp(obj,property) )will be able to either return the property value or "", and of course you can expand this into something similar to https://www.npmjs.com/package/jsonpath

Just for reference, jsperf tests a number of variants: 
http://jsperf.com/array-indexof-vs-object-s-in-operator/4

Fastest method being:

if (typeof obj['that'] !== "undefined") {
  // found
}

For very large datasets one could also look at bloom filters, e.g: https://www.jasondavies.com/bloomfilter/