standard libs can be loaded using import syntax. - import common way - import() dynamic async - importNow() sync for script Built In Modules aka JavaScript Standard Library (@yosuke_furukawa) No11: 60s Motivation Solution Import Semantics Contents No More !! Global property !!! - window - global Run Anywhere - Browser/Node/etc Namespace: `js:` reserved. - IANA register Module Freeze: - Object unextendable - enforce Object.freeze 本日の和気あいあいスレ https://github.com/tc39/proposal- built-in-modules/issues/16 - URL - Array / Set / etc - 個人的に欲しい: LinkedList, BinaryHeap, collection
proposal-readonly-collections (@sadnessOjisan) No25: 30s https://github.com/tc39/agendas/blob/master/2019/ 10.readonly-collections-as-recorded.pdf ES3 everything mutable ES6 all collections mutable class AbstractMap { // A FixedMap, not necessarily fresh, whose state is this map's current // state. snapshot() :FixedMap; // A fresh Map whose initial state is this map's current state. diverge() :Map; // A ReadOnlyMap, not necessarily fresh, whose state is a read only // view of this map's current state. readOnlyView() :ReadOnlyMap(); // query-only methods of Map ... } マスタの管理とかがしやすくなるよ！ ReadOnlyMap, FixedMap 例としてMap
proposal-string-dedent (@sadnessOjisan) No52: 30s ♂ ♂ class MyClass { print() { console.log(`create table student( id int primary key name text )`) } } class MyClass { print() { console.log(` create table student( id int primary key name text ) `) } } class MyClass { print() { console.log(``` create table student( id int primary key, name text ) ```) } }
No54: 30s throw expression (Stage 2) @arayaryoma // throw statement function hello(name) { if (name === undefined) { throw new Error("arg: name must be passed"); } console.log(`Hello, ${name}`); } // throw expression function hello(name = throw new Error("arg: name must be passed")) { console.log(`Hello, ${name}`); } hello(); // Error 'arg: name must be passed' // throw statement const result = obj?.a?.b; if (result === undefined || result === null) { throw new Error("obj.a.b is undefined"); } // throw expression const result2 = obj?.a?.b ?? throw new Error("obj.a.b is undefined"); Initial commit: 2017/7/16 Latest commit: 2018/1/24 Champion: @rbuckton https://github.com/tc39/proposal-slice-notati on throw を式で書ける 関数のデフォルト値として定義したり ?. や ?? と組み合わせると便利 引数がなかったら throwする プロパティがなかったら throwする
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