Moving Web forward: Part I — ECMAScript 201x
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This document summarizes the history and progression of ECMAScript/JavaScript standards from 1996 to the present. It outlines the stages of proposals for ECMAScript 2017 and beyond, including features like async functions, object property descriptors, and import(). Future proposals discussed include class fields, decorators, and private fields. The document emphasizes ongoing work by the TC39 committee to develop the language in a standards-driven process.
Moving Web forward: Part I — ECMAScript 201x
- 1. Moving Web forward part i — ECMAScript 201x Sergey Rubanov JavaScript Samurai November 5-6, 2016 KharkivJS #7
- 2. previously on moving web forward part 0 — harmony 2
- 3. 1996 3
- 4. Netscape: we need a language to be able to change pictures in browsers! Brendan: pfff lol easy Microsoft: NOT BAD 4
- 5. Brendan: Holy shhh… Microsoft: NOT BAD 5
- 6. 2000s 6
- 7. Brendan: Yo! I wanna add classes, a module system, optional type annotations and static typing! And algebraic data types! NO 7
- 10. I like it
- 11. 2015 11
- 14. ES2016 14
- 15. ES2016 features • Exponetiation operator (**) • Array.prototype.includes 15
- 16. ES2016 support16
- 17. ES2017 17
- 18. ES2017 features • Object.values / Object.entries • String padding • Object.getOwnPropertyDescriptors • Trailing commas in function parameter lists and calls • Async Functions 18
- 21. Object.getOwnPropertyDescriptors • Object.assign directly accesses properties and symbols instead of their descriptors • composition over classes 21
- 22. Trailing commas in function syntax 22
- 23. Async functions • based on promises and generators • make asynchronous things look like synchronous 23
- 24. ES2017 support24
- 25. Next TC39 Meetings • 55th meeting of TC39 • Host: Facebook, Menlo Park, CA • Dates: Tuesday, 29 November 2016 to Thursday, 01 December 2016 • 56th meeting of TC39 • Host: TBD • Dates: 2017-01-?? to 2017-01-?? 25
- 26. Spec revisions and scheduling • February 1: Candidate Draft is produced. • February - March: 60 day royalty-free opt-out period. • March TC39 Meeting: stage 4 proposals are incorporated, final semantics are approved, and the new spec version is branched from master. Only editorial changes are accepted from this point forward. • April-June: ECMA CC and ECMA GA review period. • July: Approval of new standard by the ECMA General Assembly 26
- 28. Stage 3 • SIMD • global • Rest/Spread Properties • Asynchronous Iteration • Function.prototype.toString revision • Lifting Template Literal Restriction 28
- 29. SIMD • proposed by Google and Intel • came from Dart • based on Typed Arrays • x86 with SSE, ARMv7 with Neon • may be useful in 3D graphics, video processing, physics simulations, cryptography, and other domains 29
- 30. SISD vs SIMD 30
- 31. SIMD 31
- 32. global • System.global previously • no more Function('return this’)()! • adds portability 32
- 33. 33
- 36. 36
- 37. global is • writable • non-enumerable • configurable 37
- 39. Asynchronous iteration 39 Sync iterator: Async iterator:
- 40. Asynchronous iteration 40 • Symbol.asyncIterator well-known symbol • for-await-of statement
- 42. Definitely ES2018 or never or later 42
- 43. Stage 2 • function.sent metaproperty • Legacy RegExp features in JavaScript • RegExp Unicode Property Escapes • String.prototype.trimStart and String.prototype.trimEnd • Shared memory and atomics • Promise.prototype.finally • Public Class Fields • Decorators • import() 43
- 44. Promise.proptotype.finally • pass callback once instead of declaring one function twice or create a variable for it • callback will not receive any arguments • will be resolved or rejected with previous promise’ value • or will reject if it throws or returns rejected promise 44
- 45. Public class fields • static properties • class fields 45
- 47. Class fields 47
- 48. Decorators 48 @frozen class Foo { @configurable(false) @enumerable(true) method() {} } decorators
- 49. import() • dynamic imports • returns promise for the module namespace object • specifier can be an expression • works in both scripts and modules • System.import() previously • await import form (instead of nested import declarations) 49
- 50. Stage 1 • Date.parse fallback semantics • export * as ns from "mod"; statements • export v from "mod"; statements • String.prototype.matchAll • Math Extensions • Generator arrow functions (=>*) 50
- 51. Stage 1 • of and from on collection constructors • WeakRefs • Frozen Realms • Private Fields • Observable • Cancelable Promises 51
- 52. Private fields 52
- 53. Observable 53
- 54. Observable 54
- 55. Observable 55
- 56. Observable 56
- 57. Observable 57
- 58. Cancelable Promises • a new class, Cancel, which does not derive from Error • try { ... } else (e) { ... } syntax, which ignores instances of Cancel • a new Promise method, promise.else(onRejected), which ignores instances of Cancel 58
- 59. Stage 0 • don’t use it in production • it is not a maturity stage • no guarantees 59
- 60. babel-preset-env ✨ Autoprefixer for Babel ✨ 60
- 61. babel-preset-env • browserlist • ECMAScript compatibility tables (ES2015 and ES2016+ tabs) • Babel plugins 61
- 62. babili ✨ ES6+ minificator ✨ 62