ECMAScript - Speaker Deck

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ECMAScript 2016/11/20 ALT

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ࣗݾ঺հ about_hiroppy abouthiroppy TEAMS

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JavaScriptͷඪ४ ECMAScript Ecma International - ECMA-262 - ECMA-402 speciﬁcations ecma-international.org /publications/standards/Standard

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Editions(only ECMA-262) • 1996/06 - ECMA-262 (ES 1) • 1998/08 - ECMA-262 (ES 2) • 1999/12 - ECMA-262 (ES 3) • 2009/12 - ECMA-262 (ES 5) • 2011/06 - ECMA-262 (ES 5.1) • 2015/06 - ECMA-262 2015 (ES 6) • 2016/06 - ECMA-262 2016 (ES 7) • 2017/?? - ECMAScript 2017 (8th Edition) developer.mozilla.org/ja/docs/Web/JavaScript/Language_Resources

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Editions(only ECMA-262) • 1996/06 - ECMA-262 (ES 1) • 1998/08 - ECMA-262 (ES 2) • 1999/12 - ECMA-262 (ES 3) • 2009/12 - ECMA-262 (ES 5) • 2011/06 - ECMA-262 (ES 5.1) • 2015/06 - ECMA-262 2015 (ES 6) • 2016/06 - ECMA-262 2016 (ES 7) • 2017/?? - ECMAScript 2017 (8th Edition) ࠓίί ES2015͔Βຖ೥ϦϦʔε  ͞ΕΔΑ͏ʹܾఆ͞Εͨ ࡦఆத

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ECMA TC39 ECMAScriptͷඪ४ԽΛ  ߦ͏ҕһձ ओཁͳϒϥ΢βϕϯμʔ  ͷ୅දͳͲ͕ࢀՃ͠  ٞ࿦͍ͯ͠Δ

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TC39 Process stage-0 stage-1 stage-2 stage-3 stage-4 Strawman Proposal Draft Candidate Finished tc39.github.io/process-document

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TC39 Process stage-1 stage-2 stage-3 stage-4 tc39.github.io/process-document stage-0 Strawman ΞΠσΞ tc39/proposalsͷstage-0΁  PRΛग़͢ɻ TC39 championΛऔಘ͠ tc39/proposals/blob/master/CONTRIBUTING.md#proposals

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TC39 Process stage-0 stage-2 stage-3 stage-4 tc39.github.io/process-document Proposal stage-1 ௥Ճ͢ΔͨΊͷέʔε࡞੒  (polyﬁlls / demos) જࡏత՝୊ͷಛఆ

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TC39 Process stage-0 stage-1 stage-3 stage-4 tc39.github.io/process-document Draft stage-2 ECMAScriptඪ४Λ࢖༻͠  ߏจͱηϚϯςΟοΫͷ  ਖ਼֬ͳઆ໌Λ͢Δɻ

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TC39 Process stage-0 stage-1 stage-2 stage-4 tc39.github.io/process-document stage-3 Candidate ࣮૷΍Ϣʔβ͔Βͷ  ϑΟʔυόοΫΛٻΊΔɻ ͢΂ͯͷηϚϯςΟοΫɺ  ߏจɺٴͼAPI͕ܾఆ͞ΕΔɻ

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TC39 Process stage-0 stage-1 stage-2 stage-3 tc39.github.io/process-document stage-4 Finished ਖ਼ࣜͳECMAScriptඪ४ʹ  ؚΊΔ४උ͕Ͱ͖͍ͯΔ͜ͱ  Λࣔ͢ɻ test262Ͱ࢖༻γφϦΦςετ͕  ड୚ɺϚʔδ͞ΕΔඞཁ͕͋Δɻ 2ͭҎ্ͷޓ׵࣮૷͕ඞཁɻ

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stage-4ͷProposal͸ਖ਼ࣜʹ  ࣍ظECMAScriptͷ࢓༷ͱͳΔ

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ES2016 • Array.prototype.includes • Exponentiation Operator const arr = [1, 2, 3]; if (arr.includes(2)) { console.log('aru!'); } if (2**3 === 8) { console.log('**'); }

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ES2017 • String.prototype.padStart  String.prototype.padEnd • Object.values  Object.entries • Object.getOwnPropertyDescriptors • Trailing Commas in Function Param Lists • Async Functions

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string padding 'a'.padStart(5); // " a" 'a'.padEnd(5); // "a " 'a'.padStart(3, 'b'); // "bba" 'a'.padEnd(3, 'b'); // "abb" จࣈຒΊΛߦ͏ let num = 1; // `0${num}`.slice(-2); // 01 // ☺ num.toString().padStart(2, 0); // 01 tc39/proposal-string-pad-start-end

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Object.values/Object.entries const obj = { name: 'hello', age: 24 }; Object.values(obj); // Array [ "hello", 24 ] Object.entries(ob); // Array [ [ "name", "hello" ], [ "age", 24 ] ] tc39/proposal-object-values-entries

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Object.  getOwnPropertyDescriptors ࢦఆͨ͠ΦϒδΣΫτͷ  ͢΂ͯͷPropertyDescriptors  Λऔಘ͢Δ attributes - value - writable - get - set - conﬁgurable - enumerable const obj = { name: 'hello', age: 24 }; Object.getOwnPropertyDescriptors(obj); // Object { name: Object, age: Object } /* Object { name: { configurable: true, enumerable: true, value: "hello", writable: true }, age: ... } */ tc39/proposal-object-getownpropertydescriptors

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Trailing Commas   in Function Param Lists ΧϯϚΛڐ༰͢Δ͜ͱʹΑΓ  มߋ࣌ʹ࠷ޙඌͷϓϩύςΟ  ͷΞοϓσʔτ  (ΧϯϚΛ෇͚Ճ͑Δ)Λ๷͙ function post( p1, p2, ) {} post( 'hoge', 'fuga', ); tc39/proposal-trailing-function-commas

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Async Functions tc39/proposal-async-iteration import 'babel-polyfill'; (async () => { const str = await update(); console.info(str); })().catch((err) => console.error(err)); function update() { return new Promise((resolve, reject) => { setTimeout(() => resolve('finished!!'), 100); }); } ඇಉظͳॲཧΛಉظత  ʹهड़͢Δ͜ͱ͕Մೳ

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JavaScript͸͜Ε͔Β΋  ͲΜͲΜਐԽ͍͖ͯ͠·͢ʂ

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Links • tc39/ecma262 • tc39/proposals • tc39/agendas • tc39/tc39-notes • kangax.github.io/compat-table/es6/