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Functional Javascript Talk

WTfunctional?

I thought I was using functions!?!

FP is a set of techniques that can be used to write leaner, more testable code.

  • Comes from Math - Category Theory.
  • Not new - Lambda Calculus/Alonzo Church 1940s
  • You can write Functional JS, because Functions are First Class
    • pass'em in, or return them from fn's
    • higher-order fn's wrangle other fn's

Functional Programming is a Cult. But you can get lots of benefits w/o joining

Major Ideas

  • lots of small functions
    • really. lots. trust me...
  • PURE as the driven snow
  • But let's cheat - "PURE-ASYNC FNS" because let's face it we're working on the web
  • separate code that manipulates data from code that fetches data
  • use small fn's w/ our friends MAP and REDUCE
  • COMPOSE functions using other functions
    • partial application & currying

Starting off easy...

map and reduce with simple fn's

Add some handy utils getProp and getPropWithDefault

Start thinking about separating concerns - fetch data from transforming data from presenting data

Example App

NoCo Trail status app is map-centric and sloooow to load over 3G. What's more, we can easily show trail status in a table, which is much much faster to load than a whole map

Steps:

  • fetch status info from feature service(s)
    • the goal here is super lean app, so we'll just use fetch, but we could use agrjs if we want more comprehensive features such as authentication
  • apply transforms:
    • normalize the schemas
    • coalesce records down to individual trails
    • format for display
  • hand to React component to render