javascript - javascript global view

JavaScript - overview



TC39 webpage on

Ecma TC39 on GitHub

Technical Committee 39. Caretaker for many standards: ECMAScript (ECMA-262), Intl (ECMA-402), JSON (ECMA-404), etc.

The JS Foundation

The JS Foundation

The JS Foundation supports some of the most important projects in the JavaScript ecosystem.

Non exhaustive list of supported projects :

  • ESLint
  • jQuery
  • grunt
  • mocha
  • QUnit
  • ...

ECMAScript Norms

Written by TC39.

ECMA is an international standards body (much like ISO, IETF, W3C or WHATWG, for instance).

Wikipedia, Sources

ECMA-262 publications

Listed on the ECMA internatinal website.

Nom Edition Publication date Liens
ES1 ECMA-262 1997 PDF
ES2 ECMA-262 1998 PDF
ES3 ECMA-262 1999 PDF
ES4 ECMA-262 never Abandonned
ES5 ECMA-262 2009 PDF
ES5.1 ECMA-262 2011 PDF, HTML, Annotated HTML
ES6 ECMA-262 2015 2015 PDF, HTML, ES6 features list, ES6 Features list over ES5
ES7 ECMA-262 2016 2016 HTML
ES8 ECMA-262 2017 2017 HTML
ES9 ECMA-262 2018 2018 HTML
ES.Next ECMA-262 2019 2019 ? Draft, Feature watch: ECMAScript 2019

Publication announced in the ECMA news page.

Occurs following a general assembly meeting. The last to date was the 115th General Assembly held in Geneva, June 27, 2018.

They approved the ECMA-262 9th edition - ECMAScript® 2018 Language Specification.

The TC39 Process

The TC39 Process

Stage Description
0 Strawman "It’d be dandy if we had a unicorn operator (🦄) to…"
1 Proposal A TC39 member “champions” the proposal. General API look and feel hammered down, and many/most cross-cutting concerns addressed.
2 Draft Initial spec text, covers all critical aspects and technical semantics.
3 Candidate Spec complete, verified by appropriate reviewers and greenlighted. API finalized, no stone left unturned.
4 Finished Full Test262 coverage, 2+ shipping implementations (e.g. V8 + SpiderMonkey), significant real-world usage feedback, Spec Editor imprimatur. Usually goes into the next feature freeze (January or March).

ECMAScript proposals are tracked in a dedicated repository on github.

The file can be seen as a changelog between specs yearly versions.


ECMAScript needs an engine to be executed.

Theses Engines are used in browsers or server side.

Engines and browsers usage

Engine Browser/Server
V8 (blog officiel) Chrome, NodeJS
SpiderMonkey Gecko (Firefox)
JavascriptCore Webkit (Safari)
Chakra MS Edge
Carakan Opera still 2013


Just In Time. An engine like V8 compile JavaScript code into machine code on the fly instead of interpreting it like old engines.

How the V8 engine works? - - 20130429

Chrome V8 -

A crash course in just-in-time (JIT) compilers - - Lin Clark - 20170228


explain diff between interpretation vs compilation and how JIT plugs into this.

interpreter better startup but slower runtime (compile stupidly every LoC on the fly)

compiler slower startup but there is lots of room for optimizations

JIT tries do be between them getting the best of the 2 worlds

Un petit cours accéléré de compilation à la volée (JIT) - - 20170308

trad fr du précédent

Features Comparators / Lists

tooling lists - states of js

So we collected data from over 20,000 developers, asking them questions on topics ranging from front-end frameworks and state management, to build tools and testing libraries.

The state of js 2017

JavaScript parsers

AST (Abstract Syntax Tree)

AST is for Abstract Syntax Tree. The concept is transverse to all programming languages. Cf wikipedia def for example.


An online tool to visualize the AST of the pasted code.

Bundlers (webpack, ...) and Linters (ESLint, ...) make heavy use of AST parsers tools to do their job.

Babel is also using this at the point it integrates a parser in his project. This parser was called Babylon before it was merged in Babel.

ESLint is using eslint/espree.



Babel allows you to write your code in ES6/7/8/x, it will generate ES5 compliant code.

Javascript superset

Understanding ES5, ES2015 and TypeScript, 2016/03/20 :


TypeScript include ES6 specs but it enhances it with more features.


Comprendre enfin JavaScript, Thierry Chatel : Devoxx2015


So, what’s new in ES2020? : Christophe Porteneuve - Confoo Montréal 2018

Paris Web 2017 - Alors, qu'y a-t-il dans ES2020 ? - Christophe Porteneuve


Top JavaScript Frameworks & Topics to Learn in 2017 : Eric Elliot 20161210

Learn JavaScript Essentials (for all skill levels) : Eric Elliot 20140803

10 Priceless Resources for JavaScript Learners : Eric Elliot 20160421

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