TypeScript Evolution

For html5 Conference 2018

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2. "CPVU
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   w ೥݄ʹ(PPHMF͕ʮ"OHVMBS
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6. 
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7. 5ZQF4DSJQUͱ͸ w IUUQTXXXUZQFTDSJQUMBOHPSH
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   w ੩తͳܕ෇ݴޠ
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   w ΤσΟλϑϨϯυϦʔ
8. ܕνΣοΫͱਪ࿦ w ؔ਺TVNͷ໭Γ஋͸OVNCFSͰ͋Δ͜ͱΛਪ࿦͢Δ function sum(a: number, b: number) { return a + b; } console.log(sum(1, sum(1, 1))); // OK // Argument of type '"a"' is not assignable to // parameter of type 'number' console.log(sum('a', 'b'));
9. 4USVDUVBM
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   w %VDL
   5ZQJOHͷܕόʔδϣϯͷΑ͏ͳ΋ͷ
   w ܕͷܧঝؔ܎͸ؾʹͤͣɺܕ͕΋͍ͬͯΔϝιουɾϓϩ ύςΟͷ߹கͷΈΛؾʹ͢Δ
10. 4USVDUVBM
    4VCUZQJOH class Hoge { name = "Kurami"; } class Foo { name = "Quramy"; } function sayHello(obj: { name: string }) { console.log(obj.name); } sayHello(new Hoge()); sayHello(new Foo()); sayHello(new Error("error"));
11. ༨ஊ
    /PNJOBMʹ͍ͨ͠ͱ͖ w ͨ·ʹߏ଄త෦෼ܕͩͱࠔΔ͜ͱ͕͋Δ
    w QSJWBUFϑΟʔϧυΛ࢖͏ϋοΫͰճආ͢Δ class DateISOString { private _ = Symbol("DateISOString"); readonly isoString = new Date().toISOString(); } function hoge(x: DateISOString) { console.log(x.isoString); } hoge(new DateISOString()); hoge({ isoString: "hoge" }); // Error
12. 4USJDU
    DIFDL w TUSJDUΦϓγϣϯʢσϑΥϧτͰPOʣΛ෇͚͓ͯ͘ͱɺݎ ࿚ͳνΣοΫ͕Մೳʹ function hoge(x?: string) { //Object is possibly 'undefined'. return x.trim(); } function hoge(x?: string) { if (!x) return ""; return x.trim(); // OK }
13. BMMPXKTDIFDLKT w ৽͘͠ϓϩδΣΫτΛ࡞Δͱ͖͸ɺTUSJDU
    ͰΑ͍
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    w BMMPXKTDIFDLKT
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14. ϥΠϒϥϦͷܕఆٛ w ༗໊ͳϥΠϒϥϦ͸
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    !UZQFϥΠϒϥϦ໊
    Ͱܕఆٛ ͕ެ։͞Ε͍ͯΔ npm i @types/node import path from "path"; export function hoge() { const x = path.join("src", "main.ts"); }
15. !UZQFT w IUUQTHJUIVCDPN%FpOJUFMZ5ZQFE%FpOJUFMZ5ZQFE
16. 3FMFBTF
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    w 
    
    
    ͷΑ͏ͳNJOPS
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    w CMPHͰഁյతมߋʹ͍ͭͯΞφ΢ϯε͕͋ΔͷͰɺͦΕΛ ΑΜͰ͔ΒVQEBUF͢ΔͱΑ͍
17. #SFBLJOH
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18. 5$ͱͷ݉Ͷ߹͍ w جຊతʹ5$ͰTUBHFʹͳͬͨ࢓༷͕औΓࠐ·ΕΔ
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    w #JH*OU const i = 60_000;
19. ͍͔ͭ͘ͷྫ֎ w FYQFSJNFOUBM%FDPSBUPS
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    w WY
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    w KTYSFBDU
    w WY
    ͔Βར༻ՄೳɻΈΜͳେ޷͖+49
20. 
    ͜͜೥ͷ৽ػೳ
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21. $PNQJMFS
22. FT.PEVMF*OUFSPQ
23. FT.PEVMFT*OUFSPQ w ೥Նࠒʹ/PEFKTͷ&4
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    w ৄ͘͠͸
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24. FT.PEVMFT*OUFSPQ w /PEFKTͰ͸ɺ$PNNPO
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    JNQPSU͢ΔͱΤ ϥʔʹ /* hoge.mjs */ import { readFile } from "fs"; $ node --experimental-modules hoge.mjs SyntaxError: The requested module does not provide an export named ‘readFile' at checkComplete (internal/loader/ModuleJob.js:75:27) at moduleJob.linked.then (internal/loader/ModuleJob.js: 58:11) at <anonymous>
25. FT.PEVMFT*OUFSPQ w Ұํɺ5ZQF4DSJQUͰ͸ඇ&4
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    JNQPSUͰهड़͢Δ͔͠ͳ͔ͬͨ import * as fs from "fs"; import { readFile } from "fs";
26. FT.PEVMFT*OUFSPQ w WYҎ߱Ͱ͸ɺ$PNNPO+4͔ΒͷEFGBVMU
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27. *NQSPWF
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28. .BQQFE
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    Λ෇༩͢Δ͜ͱ ͸Ͱ͖ͯ΋ɺղআ͢Δ͜ͱ͸Ͱ͖ͳ͔ͬͨ type Optional<T> = { [P in keyof T]?: T[P] }; type ReadOnly<T> = { readonly [P in keyof T]: T[P] };
29. 
    
    
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    NPEJpFS w
    
    
    ͷ෇༩Ͱɺ࡞༻ͷ޲͖ ෇͚Δ֎͢ ΛදݱՄೳʹ type Optional<T> = { [P in keyof T]+?: T[P] }; type Strict<T> = { [P in keyof T]-?: T[P] }; type ReadOnly<T> = { +readonly [P in keyof T]: T[P] }; type Mutable<T> = { -readonly [P in keyof T]: T[P] };
30. 
    
    
    XJUI
    NPEJpFS type Strict<T> = { [P in keyof T]-?: T[P] }; // Property 'name' is missing in type '{}' // but required in type 'Strict<{ name?: string | undefined; }>'. const x: Strict<{ name?: string }> = { };
31. $POEJUJPOBM
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32. $POEJUJPOBM
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    w "TTJHOBCMFΛ৚݅ͱͯ͠෼ذ͢ΔܕΛදݱՄೳ
    w ʮܕ5͕ܕ6ͷ෦෼ܕͰ͋Ε͹ɺܕ9ɺͦ͏Ͱͳ͚Ε͹ܕ:ʯ ͱ͍͏ҙຯ type MyType<T, U, X, Y> = T extends U ? X : Y;
33. -FUT
    UZQF w ༡ΜͰΈΑ͏
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    w %J⒎
    w %J⒎͸ͲΜͳܕͰ͠ΐ͏͔ʁ type DiffKey<K1, K2> = K1 extends K2 ? never : K1; type $Diff<T, U> = { [P in DiffKey<keyof T, keyof U>]: T[P]; };
34. %JTUSJCVUJPO w $POEJUJPOBM
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    w type DiffKey<K1, K2> = K1 extends K2 ? never : K1; let key: DiffKey<("name" | "age"), "age">; // ("name" extends "age" ? never : "name") // | ("age" extends "age" ? never : "age") // = ("name" | never) // = "name"
35. $POEJUJPO
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    w .BQQFE
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36. %J⒎ͷਖ਼ମ w 'MPX
    UZQFʹಉ໊ͷ6UJMJUZ
    UZQF͕͋Γ·͢ type DiffKey<K1, K2> = K1 extends K2 ? never : K1; type $Diff<T, U> = { [P in DiffKey<keyof T, keyof U>]: T[P]; }; const defaultProps = { age: 0 }; let requiredProps: $Diff<{ name: string; age: number; }, typeof defaultProps>; requiredProps = { name: "Quramy" };
37. 5ZQF
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38. 5ZQF
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39. *OGFS
    BOE
    $BQUVSF w ਖ਼نදݱͷΩϟϓνϟϦϯάʢάϧʔϓԽʣͱࣅ͍ͯΔ
    w Ϛονͨ͠άϧʔϓ෦෼Λޙ͔Βར༻Ͱ͖Δ const regexp = /hoge(\d+)/; const hit = "hoge10".match(regexp); console.log(hit[1]) // 10
40. *OGFS
    BOE
    $BQUVSF w 5͕ؔ਺Ͱ͋Ε͹ɺͦͷ໭Γ஋ͱͯ͠ਪ࿦͞ΕΔܕ͕3ʹ֨ ೲ͞ΕΔ type Return<T> = T extends (...args: any[]) => infer R ? R : never; let r: Return<() => number>; // typeof r = number
41. 3FEVYͬΆ͍ΞϨ type Return<T> = T extends (...args: any[]) => infer R ? R : never; type AppState<T> = { [P in keyof T]: Return<T[P]> }; const reducers = { name: (state: string, action: any) => state, age: (state: number, action: any) => state, }; let appState: AppState<typeof reducers>; // typeof appState = { name: sting, age: number }
42. ࢖͍͗͢ʹ஫ҙ w $POEJUJPOBM
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    w Τϥʔϝοηʔδ͕ͲΜͲΜಡΈͮΒ͘ͳΔ
    w ϨϏϡΞ͕ͨ·ͬͨ΋Μ͡Όͳ͍
43. VOLOPXO
44. VOLOPXO
    UZQF w WY
    Ͱಋೖ
    w VOLOPXO͸͢΂ͯͷܕ͕BTTJHOBCMF
    w VOLOPXO
    UZQF͸ɺUZQF
    BTTFSUJPO͠ͳ͍ͱԿ΋Ͱ͖ͳ͍ function hoge(x: unknown) { if (typeof x === "string") { console.log(x.toLowerCase()); } } hoge(10); hoge("foo");
45. 5VQMFT
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    SFTU
    QBSBNFUFST
    BOE
    TQSFBE
    FYQSFTTJPOT
46. 5VQMFT
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    TQSFBE
    FYQSFTTJPOT w WYͰɺؔ਺Ҿ਺ʹؔ܎͢Δܕͷهड़ྗ͕ڧԽ͞Εͨ
    w 3FTU
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    w 4QSFBE
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    w 0QUJPOBM
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    w 3FTU
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47. 3FTU
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    UZQFͷΈ͕ڐ༰
    w WY
    ͔Β͸5VQMF
    UZQF΋ར༻Մೳʹ function hoge(...args: any[]) { const a1 = args[0]; const a2 = args[1]; const a3 = args[2]; } function foo(...args: [string, number]) { const a0 = args[0]; // string const a1 = args[1]; // number const a2 = args[2]; // error }
48. 4QSFBE
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    FSSPSʹͳͬͯ͠·͍ͬͯͨ
    w WY
    ͔Β͸5VQMF
    UZQF΋ར༻Մೳʹ declare function foo(a: number, b: number): void; const args1 = [1, 2] as [number, number]; foo(...args1); const args2 = [1, "bar" ] as [number, string]; // Argument of type 'string' is not assignable to // parameter of type 'number'. foo(...args2);
49. (FOFSJD
    SFTU
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    1BSBNFUFSTʹ૯শܕ͕ར༻Մೳʹ
    w +BWB4DSJQU
    GVODUJPOͷCJOEDBMMBQQMZͱͷ਌࿨ੑ޲্
 ޙड़ͷ
    TUSJDU#JOE$BMM"QQMZ
    ͷૅ declare function curry<T, U extends any[], R>( fn: (x: T, ...args: U) => R ): (x: T) => (...args: U) => R; const sum = (a: number, b: number) => a + b; const bound = curry(sum)(1); const x = bound(2); // type of x = number const error = bound("hoge"); // error
50. 0QUJPOBM
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    5ZQFͰड͚ΕΔΑ͏ͳͬͨ͜ ͱʹΑΔ෭࢈෺ type Tuple = [number, string?]; const x1: Tuple = [1]; const x2: Tuple = [1, "foo"];
51. 3FTU
    FMFNFOUT
    JO
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    UZQFT w 5VQMF
    5ZQFதʹ3FTUͳUZQFΛදݱͰ͖ΔΑ͏ʹͳͬͨ
    
    w ؔ਺ͷ3FTU
    1BSBNFUFSTͱͯ͠΋ར༻Մೳ function hoge<T extends any[]>(...args: T) { return args; } const arr = [1, 2, 3]; const v = hoge("hoge", ...arr); // typeof v = [string, ...number[]] type Hoge = [string, ...number[]];
52. .BQQFE
    UVQMF
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53. .BQQFE
    UVQMF
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    w WY·Ͱ͸.BQQFE
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    w WY͔Β͸ʮ഑ྻཁૉࣗମʹର͢ΔϚοϐϯάʯͱ͍͏ ڍಈʹมߋ͞Εͨ
54. 
    Y type Box<V> = { value: V }; type Boxing<T>= { [P in keyof T]: Box<T[P]>; }; type User = { name: string, age: number, }; const boxedUser: Boxing<User> = { name: { value: "quramy" }, age: { value: 18 }, }; let boxedNumbers: Boxing<number[]>; boxedNumbers.concat.value([]); // ??? boxedNumbers.length.value; // ???
55. 
    Y w LFZPG
    OVNCFS<>
    ͷҙຯ͕มΘͬͨΘ͚Ͱ͸ͳ͍఺ʹ஫ҙ
    type Box<V> = { value: V }; type Boxing<T>= { [P in keyof T]: Box<T[P]>; }; const boxedNumbers: Boxing<number[]> = [ { value: 1 }, { value: 100 }, ];
56. ࢖͍Έͪ w $POEJUJPOBM
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    w
    ͓୊
    SYKTͷDPNCJOF-BUFTUؔ਺ʢ˞
    1SPNJTFBMMతͳౕʣ interface Observable<T> { subscribe(cb: (v: T) => void): void; } declare var s1$: Observable<string>; declare var s2$: Observable<number>; combineLatest(s1$, s2$).subscribe(([s1, s2]) => { console.log(s1); // typeof s1 = string console.log(s2); // typeof s2 = number });
57. ࢖͍Έͪ interface Observable<T> { subscribe(cb: (v: T) => void): void; } // Inference in conditional type type StreamType<T> = T extends Observable<infer S> ? S : never; // Mapped tuple type type Unboxing<U extends Observable<any>[]> = { [P in keyof U]: StreamType<U[P]>; }; // Generic rest parameters declare function combineLatest<U extends Observable<any>[]> (...args: U): Observable<Unboxing<U>>;
58. TUSJDU#JOE$BMM"QQMZ
59. TUSJDU#JOE$BMM"QQMZ w WYͰಋೖ
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    w WYͷ5VQMF
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    w TUSJDUΦϓγϣϯϑΝϛϦʔͷͭʢσϑΥϧτͰ0/ʣ
60. TUSJDU#JOE$BMM"QQMZ w CJOE declare function hoge(a: number, b: string): void const hoge1 = hoge.bind(null, 1); hoge1("hoge"); hoge1(); // error hoge1(1); // error hoge1("hoge", 2); // error
61. TUSJDU#JOE$BMM"QQMZ w DBMM declare function hoge(a: number, b: string): void hoge.call(null, 1, "hoge"); hoge.call(null, 1); // error hoge.call(null, "hoge"); // error hoge.call(null, 1, "hoge", 2); // error
62. TUSJDU#JOE$BMM"QQMZ w BQQMZ declare function hoge(a: number, b: string): void hoge.apply(null, [1, "hoge"]); hoge.apply(null, [1]); // error hoge.apply(null, ["hoge"]); // error hoge.apply(null, [1, "hoge", 2]); // error
63. ͜͜೥ͷ৽ػೳ
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    4FSWJDFฤ
64. -BOHVBHF
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65. 0SHBOJ[F
    *NQPSU
66. 0SHBOJ[F
    *NQPSU w WYͰಋೖ
    w UTTFSWFS -BOHVBHF
    4FSWJDF
    ʹ
    PSHBOJ[F*NQPSU
    ίϚϯ υ͕௥Ճ͞Εͨ
    w UTMJOUͷOPVOVTFEWBSJBCMFT JNQPSU ͷpY૬౰΋΍ͬͯ͘ ΕΔ
67. %FNP /* before */ import { hoge } from "./lib"; import { foo } from "./lib"; // no used import import { bar } from "./lib"; hoge(); foo(); /* after */ import { hoge, foo } from "./lib"; hoge(); foo();
68. $PEF
    'JY
    4VHHFTUJPO
69. ,JOE
    PG
    &SSPST w 5ZQF4DSJQUͷΤϥʔ͸΋ͱ΋ͱछྨ
    w 4ZOUBY
    &SSPS
    ͦ΋ͦ΋จ๏ͱ͓͔͍ͯ͠͠΋ͷ
    w 4FNBOUJD
    &SSPS
    ܕෆ੔߹ͳͲ
70. &SSPS
    
    $PEF
    pY w UTTFSWFS -BOHVBHF
    4FSWJDF ʹ͓͚ΔΤϥʔpYͷྲྀΕ
     HFU4VQQPSUFE$PEF'JYFT
    ίϚϯυͰ-BOH
    4FSWJDF͕ରԠՄೳͳ ΤϥʔίʔυͷҰཡΛऔಘ͓ͯ͘͠
     HFU&SSPS
    ίϚϯυͰϑΝΠϧͷΤϥʔΛ-BOH
    4FSWJDF΁໰͍߹Θ ͤΔ
     $PEF
    'JYαϙʔτର৅ͷΤϥʔίʔυͷ৔߹ɺHFU$PEF'JYFTίϚ ϯυͰमਖ਼಺༰Λ-BOH
    4FSWJDFʹ໰͍߹ΘͤΔ
     ड͚औͬͨมߋ಺༰ 5FYU$IBOHF ΛΤσΟλͷόοϑΝʹద༻͢Δ
71. 4VHHFTUJPO
    &SSPS w ཁ͢ΔʹΤϥʔ͕ແ͍ͱɺ$PEF
    'JY͸Ͱ͖ͳ͍
    w ʮ5ZQF4DSJQUͦͷ΋ͷ͕ਪ঑͢Δॻ͖ํʯʹϦϑΝΫλ͞ ͤΔͨΊʹ͸ɺରԠ͢ΔΤϥʔίʔυ͕ඞཁ
    w Α͠ɺ৽͍͠ΧςΰϦΛ࡞Ζ͏ʂͱ͍͏͜ͱͰɺ 4VHHFTUJPO
    &SSPS͕WYͰੜ·Εͨ
72. %FNP w ౾஌ࣝ
    Τϥʔίʔυ൪୆͸4VHHFTUJPO
    &SSPS
73. 3FOBNF
    JNQPSU
    EFDMBSBUJPO
74. 3FOBNF
    JNQPSU
    EFDMBSBUJPO w WYͰಋೖ
    w *NQPSU
    GSPN
    ͷର৅෦෼ΛSFOBNFͰ͖ΔΑ͏ʹͳͬͨ /* fuga.ts */ export function fuga() { return "hoge"; } /* main.ts */ import { fuga } from "./fuga"; console.log(hoge());
75. 4VNNBSZ
76. 4VNNBSZ w $POEJUJPOBM
    UZQFͱ*OGFSFODF͸௒ڧྗ
    w 3FTU
    QBSBNFUFSTपΓͷվળ͕ҰؾʹਐΜͩ
 CJOE
    
    DBMM
    
    BQQMZ
    ͷܕνΣοΫ͸਱ʹདྷ͔ͨʂײ͋Δ
    w $PEF
    'JY΍ϦϑΝΫλؔ࿈΋Ҿ͖ଓ͖֦ॆ͕ਐΜͰ͍Δ
77. &OKPZ
    UZQJOH
    5ZQF4DSJQU
78. 5IBOL
    ZPV