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![function calculateBill(items, tax) {
let total = 0m;
for (let {price, count} of items) {
total += price * BigDecimal(count);
}
return BigDecimal.round(total * (1m + tax),
{maximumFractionDigits: 2, round: "up"});
}
let items = [{price: 1.25m, count: 5}, {price: 5m, count: 1}];
let tax = .0735m;
console.log(calculateBill(items, tax));](https://image.slidesharecdn.com/ecmascript-fest-240105140258-9a21a2cb/85/From-the-proposal-to-ECMAScript-Step-by-Step-20-320.jpg)
![// Using Combinators `and` , `or` , `with`
match (command) {
when ([ 'go', dir and ('north' or 'east' or 'south' or 'west')]): go(dir);
when ([ 'take', item and /[a-z]+ ball/ and { weight }]): take(item);
default: lookAround()
}](https://image.slidesharecdn.com/ecmascript-fest-240105140258-9a21a2cb/85/From-the-proposal-to-ECMAScript-Step-by-Step-23-320.jpg)
![const record = #{ prop: 1 };
const tuple = #[1, 2, 3];
// Simple Equality
#{ a: 1 } === #{ a:1 } // or #[1] === #[1]
// Nested Equality
#{ a: #{ b: 123 }} === #{ a: #{ b: 123 }}
// Order Independent
#{ a: 1, b: 2 } === #{ b: 2, a: 1}](https://image.slidesharecdn.com/ecmascript-fest-240105140258-9a21a2cb/85/From-the-proposal-to-ECMAScript-Step-by-Step-34-320.jpg)
![const sequence = [1, 2, 3];
sequence.toReversed(); // => [3, 2, 1]
sequence; // => [1, 2, 3]
const outOfOrder = new Uint8Array([3, 1, 2]);
outOfOrder.toSorted(); // => Uint8Array [1, 2, 3]
outOfOrder; // => Uint8Array [3, 1, 2]
const correctionNeeded = [1, 1, 3];
correctionNeeded.with(1, 2); // => [1, 2, 3]
correctionNeeded; // => [1, 1, 3]](https://image.slidesharecdn.com/ecmascript-fest-240105140258-9a21a2cb/85/From-the-proposal-to-ECMAScript-Step-by-Step-48-320.jpg)
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From the proposal to ECMAScript – Step by Step
The document outlines the process and structure of the TC39 committee, which governs the evolution of the JavaScript language through consensus-based proposals and stages. It details the roles of contributors, the various stages from initial idea to finalized specification, and examples of features under consideration. Additionally, it encourages community involvement in the development process.
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From the proposal to ECMAScript – Step by Step
- 1. From the proposalto ECMAScript Step by step @romulocintra
- 2. What’s Standards BODY andTC39 ? 1
- 3. @romulocintra They’re Avenues for unification& uniformization ● WHATWG ● W3C ● ISO ● ECMA ● Unicode ● …
- 4. @romulocintra TC39 is the Technicalcommittee that defines the JavaScript language
- 5.
- 6. 13 Delegates ● Implementers (Apple,Google, Mozilla, Microsoft …) ● Big Companies (Sony, PayPal, Netflix) ● Students and NPF (Universities, OpenJS F …) Invited Experts ● Subject matter experts ● Community representatives Contributors, Editors, Reviewers & Community Who are they ?
- 7. Glossary … ❏ ECMA ❏ECMA-262 … ❏ ECMAScript ❏ JavaScript ❏ TC-XX (TC39 , TC45) @romulocintra
- 8.
- 9. @romulocintra Consensus-based decision Diverse setof people in the committee Implementers , Practitioners, Community Experts Objections and concerns to satisfy everyone’s No stakeholder kept over another and , Backing rationales
- 10. @romulocintra STAGES Steps where proposalevolves and receives feedback 1 + 4 Stages
- 11. When 4-8 Plenary Meetings ayear Online or In person Focus Groups and Incubator Calls Monthly or Biweekly TG2 / Editors / Outreach / Proposals / Educators / Tools Monthly or Biweekly
- 12.
- 13.
- 14.
- 15. @romulocintra STAGE 0 💡 Strawperson Justan Idea Explainer, Idea under discussion, Strawperson Proposal
- 16.
- 17. @romulocintra STAGE 1 Describe theshape of a solution it’s an idea under discussion Proposal �� Devote time and have a “Champion” Demos / Polyfills Major changes
- 18.
- 19. STAGE 1 Decimal Philip Chimento,Andrew Paprocki, Jesse Alama
- 20. function calculateBill(items, tax){ let total = 0m; for (let {price, count} of items) { total += price * BigDecimal(count); } return BigDecimal.round(total * (1m + tax), {maximumFractionDigits: 2, round: "up"}); } let items = [{price: 1.25m, count: 5}, {price: 5m, count: 1}]; let tax = .0735m; console.log(calculateBill(items, tax));
- 21. STAGE 1 Pattern Matching DanielRosenwasser, Jack Works, Jordan Harband, Mark Cohen, Ross Kirsling, Tab Atkins-Bittner
- 22. match (res) { when({ status: 200, body, ...rest }): handleData(body, rest) when ({ status, destination: url }) if (300 <= status && status < 400): handleRedirect(url) when ({ status: 500 }) if (!this.hasRetried): do { retry(req); this.hasRetried = true; } default: throwSomething(); }
- 23. // Using Combinators`and` , `or` , `with` match (command) { when ([ 'go', dir and ('north' or 'east' or 'south' or 'west')]): go(dir); when ([ 'take', item and /[a-z]+ ball/ and { weight }]): take(item); default: lookAround() }
- 24. // Built-in custommatchers match (value) { when (${Number}): ... when (${BigInt}): ... when (${String}): ... when (${Array}): ... default: ... }
- 25. STAGE 1 Types Annotations DanielRossenwaver, Rob Palmer, Romulo Cintra
- 29. Optional ergonomic typeannotations in JavaScript code Types that don’t change JavaScript semantics Direct execution of statically typed code ✅ ✅ ✅ Independent evolution of JavaScript and type-checkers ✅
- 30. Runtime effects 100% Compatiblewith TS, Flow… ❌ ❌
- 31. @romulocintra STAGE 2 Draft�� Describe syntactic and semantic details Form spec language - Initial Spec Text Semantics and API are covered - not completed TC39 Expects that feature would be developed in future Experimental
- 32.
- 33. STAGE 2 Record &Tuple Robin Ricard, Rick Button
- 34. const record =#{ prop: 1 }; const tuple = #[1, 2, 3]; // Simple Equality #{ a: 1 } === #{ a:1 } // or #[1] === #[1] // Nested Equality #{ a: #{ b: 123 }} === #{ a: #{ b: 123 }} // Order Independent #{ a: 1, b: 2 } === #{ b: 2, a: 1}
- 35. @romulocintra STAGE 3 Candidate�� Refinement phase(Feedback from implementers and users), almost ready to go Completed Spec Text Have Reviewers and Editors Signed off the spec Coverage on Test262 Spec Compliant Some browser might implement under a flag
- 36.
- 38. STAGE 3 Intl.DurationFormat YouniesMahmoud, Ujjwal Sharma
- 39. new Intl.DurationFormat("fr-FR", {style: "long" }).format({ hours: 1, minutes: 46, seconds: 40, }); // => "1 heure, 46 minutes et 40 secondes"
- 40. STAGE 3 Temporal PhilippDunkel , Maggie Johnson-Pint, Matt Johnson-Pint, Brian Terlson, Shane Carr, Ujjwal Sharma, Philip Chimento, Jason Williams, Justin Grant
- 41. const yearMonth =Temporal.PlainYearMonth.from({ year: 2020, month: 10 }); yearMonth.toString() => 2020-10 yearMonth.daysInMonth; // => 31 yearMonth.daysInYear; // => 366 const monthDay = Temporal.PlainMonthDay.from({ month: 7, day: 14 }); const date = monthDay.toPlainDate({ year: 2030 }); date.dayOfWeek; // => 7 date.dayOfYear // => 195 date.daysInMonth // => 31 date.daysInYear // => 365 date.inLeapYear // => false
- 42. let calcDate =Temporal.Now.plainDateISO(); // => 2021-11-29 calcDate.add({ days : 15 }); // => 2021-12-14 calcDate.subtract({ days : 15 }); // => 2021-11-14 calcDate.equals(calcDate); // => true calcDate.equals(calcDate.add({ days : 2})); // => false
- 43. const time =Temporal.Instant.fromEpochSeconds(new Date); Temporal.TimeZone.from('Europe/Berlin').getOffsetStringFor(time); // => +01:00 Temporal.TimeZone.from('America/Vancouver').getOffsetStringFor(time); // => -08:00 Temporal.TimeZone.from('Europe/Moscow').getOffsetStringFor(time); // => +03:00
- 44. @romulocintra STAGE 4 Finished�� About to be include in the upcoming edition of ECMAScript® Merged into the Spec text Two implementations that passes acceptance tests Will be included on the upcoming Spec Shipping
- 45.
- 46. const nf =new Intl.NumberFormat("en-US", { style: "currency", currency: "CHF", maximumFractionDigits: 0, }); nf.formatRange(3, 5); // "CHF 3–5"
- 47. STAGE 4 Changearray by Copy ^ Robin Ricard, Ashley Claymore
- 48. const sequence =[1, 2, 3]; sequence.toReversed(); // => [3, 2, 1] sequence; // => [1, 2, 3] const outOfOrder = new Uint8Array([3, 1, 2]); outOfOrder.toSorted(); // => Uint8Array [1, 2, 3] outOfOrder; // => Uint8Array [3, 1, 2] const correctionNeeded = [1, 1, 3]; correctionNeeded.with(1, 2); // => [1, 2, 3] correctionNeeded; // => [1, 1, 3]
- 49. Error: .cause ClassFields, Private Instance fields & methods… .at() Object: .hasOwn() Intl.Segmenter
- 50.
- 51. Collaboration & Help Getinvolved !!! 4
- 52. @romulocintra Write test262 conformancetests Refine proposals in GitHub issues Write documentation and educational materials Provide feedback on GitHub �� �� �� ��
- 53.