JavaScript is a whole new language to learn in 2018

EcmaScript version history: The Dark Ages

• ES4 never even came out!
• Long delay between initial draft and release meant a lot of browser-specific implementation
• Things had to change

Introducing the

TC39 process

• new way of adding new features in the language
• yearly release, starting with ES2016

Five stages process

• 0 - Strawman
• 1 - Proposal
• 2 - Draft
• 3 - Candidate
• 4 - Finished - The functionality is already usable!

ES2016

• Complete feature list:
  • Array.prototype.includes
  • Exponentiation Operator
• That's it!
• First release with the new process: small release

ES2017: async/await

• new way to handle promises, integrated into the language

<code example>

ES2017: other features

• SharedBufferArray and Atomics
• Object.values/Object.entries
• String padding
• the trailing comma!!!!

ES2018:Async Iterations

• Iterating over an array of promises

<code example>

ES2018: Other features

• Rest/Spread Properties
• finally a .finally() for promises!
• new Regexp features

And what's next?

And what's next?

• Superset JSON (Stage 4: WILL be in ES2019)
• Private fields and methods (Stage 3: almost certain!)
• Decorators (Stage 2: not for now)
• Nullish Coalescing (Stage 1: maaaaybe)
• Pattern Matching! (Stage 0: well...)

JavaScript in 2018:
OOP flavor

• class-like syntax (prototypes in disguise)

• OOP keywords: static, super, extends....

• ES Modules promoting OOP-like project structures

JavaScript in 2018:
Functional flavor

• ES6 arrow functions are a delight to use
• React/Flux had a huge impact on JS app design (promoting immutability & predictability)
• Pipeline operator will be a game-changer if accepted

The era of transpilers

• Success story of Babel
• Polyfill as a service
• ES2015-2018 is usable today in IE11
• Everyone can and should use latest JS features
• npm everything
• Tooling gets mature and needs less config

Static typing

• Most agree that JS needs a type system
• Finally some viable, lasting solutions:
  • TypeScript (Microsoft) 5 y.o. birthday
  • Flow (Facebook), lighter yet powerful
• Both are thin layers over JS, easy opt-out
  That's key to success (goodbye CoffeeScript & Dart)

Strong dynamic typing

• Now possible in JS using ES6 Proxies
• flow-runtime, and why it's not such a great idea
• objectmodel.js.org short example
  (shameless self-promotion)

The rise of build tools

• 2012: laborious (shell scripting, messy ecosystem)
• 2015: manageable (node ecosystem, grunt/gulp)
• 2017: powerful (hot module reload UX, webpack)
• 2019: natural (zero config trend, parcel, fwk CLI)

Predictions about JS Future
(conclusion ?)
2020, the evergreen era

• IE is dead (is it ?)
• less transpiling is needed, but we got used to it
• build tools / transpilers became smart & transparent
• transpiling as a service and smart degradation for older devices or mobile
• most of frameworks job is now done at build time, the runtime size penalty gets close to zero

Predictions about JS Future
(conclusion ?)
2025, the interop era

• npm is bloated and changed its model, or has a competitor. JS is no longer the only option
• WebAssembly arrived quietly and has great interop with JS. They are used together as a compil target
• JS engines get optimized for subsets of the language, improving perf and compile time with the right tooling
• JS has split in 2 parts: one as a compilation target (compressed, subsetted, prepacked, WASM-boosted), one as a language (probably close to TypeScript/ReasonML)