Advanced built-in types / #kansaits 1

kansai.ts #1 ( https://kansaits.connpass.com/event/130120/ ) でTypeScriptの便利なbuilt-in typesについて話をしました。
質問はTwitter( https://twitter.com/shisama_ )までお願いいたします。

Transcript

1. Advanced built-in types you may not know Masashi Hirano @shisama kansai.ts #1
2. ฏ໺ ণ࢜ / Masashi Hirano @shisama_ @shisama Node.js Core Collaborator ؔ੢NodeֶԂOrganizer
3. TypeScriptʹbuilt-in͞Ε͍ͯΔศརͳܕʹ ͍ͭͯ঺հ͠·͢ʂ
4. https://www.typescriptlang.org/docs/handbook/advanced-types.html ެࣜͷAdvanced TypesಡΜͩ͜ͱ͋Δ?
5. Advanced Types • Conditional Types΍Mapped TypesͳͲෳࡶͳܕ΍Union Types ͳͲศརͳه๏ͳͲΛ঺հ͍ͯ͠Δެࣜͷϖʔδ • ࠓճ͸ͦͷத͔Βbuilt-in͞Ε͍ͯΔศརͳܕΛ঺հ͠·͢
 ※ܕఆٛΛಡΉʹ͸Conditional Types΍Mapped Types͕ಡ ΊΔඞཁ͕͋Γ·͢ɻ
6. https://github.com/microsoft/TypeScript/blob/master/src/lib/es5.d.ts 5ZQF4DSJQUͷ(JU)VCϦϙδτϦͷ
   TSDMJCFTEUTʹఆ͕ٛ͋Δ
7. type Partial<T> = { [P in keyof T]?: T[P]; };
8. type Partial<T> = { [P in keyof T]?: T[P]; }; LFZPG͸5 ΦϒδΣΫτ ͷϓϩύςΟ໊Λऔ͍ͬͯΔ
   ϓϩύςΟʹ Λ෇༩ͯ͠PQUJPOBMʹ͍ͯ͠Δ
   JO͸5ͷϓϩύςΟ໊Λ1ʹ֨ೲ͍ͯ͠Δɻ
   5<1>͸ࢦఆͨ͠ϓϩύςΟͷܕ
9. Partial ͢΂ͯͷϓϩύςΟΛ0QUJPOBMʹ͢Δ
10. Partial
11. Partial 6TFS͸JE͕ඞਢͳͷͰۭΦϒδΣΫτ͸ίϯ ύΠϧΤϥʔʹͳΔɻ
 1BSUJBM6TFS͸͢΂ͯͷϓϩύςΟ͕0QUJPOBMʹͳΔͨ ΊۭΦϒδΣΫτΛ୅ೖͰ͖Δ
12. type Required<T> = { [P in keyof T]-?: T[P]; };
13. type Required<T> = { [P in keyof T]-?: T[P]; };  ͸PQUJPOBMͷϓϩύςΟΛOPOPQUJPOBMʹ͢Δ
    1BSUJBMͷٯͰ ΛऔΓআ͍͍ͯΔ
14. Required ͢΂ͯͷϓϩύςΟΛOPOPQUJPOBMʹ͢Δ
15. Required
16. Required ͢΂ͯͷϓϩύςΟ͕OPOPQUJPOBMͳͷͰ JE͸লུͰ͖ͳ͍
17. type Readonly<T> = { readonly [P in keyof T]: T[P]; };
18. type Readonly<T> = { readonly [P in keyof T]: T[P]; }; ϓϩύςΟͷલʹSFBEPOMZΛॻ͘ͱͦͷϓϩύςΟ͸ಡ ΈऔΓઐ༻ʹͳΔ
19. Readonly ͢΂ͯͷϓϩύςΟΛSFBEPOMZʹ͢Δ
20. Readonly
21. Readonly ͢΂ͯͷϓϩύςΟΛSFBEPOMZͷͨΊ ୅ೖෆՄೳ
22. type Pick<T, K extends keyof T> = { [P in K]: T[P]; };
23. type Pick<T, K extends keyof T> = { [P in K]: T[P]; }; ,ʹࢦఆͰ͖Δͷ͸5ͷϓϩύςΟ໊ͷΈɻ5ʹແ͍ϓϩ ύςΟ໊Λࢦఆ͢ΔͱΤϥʔʹͳΔ
24. Pick ࢦఆͨ͠ϓϩύςΟͷΈ࢒͢
25. Pick
26. Pick ࢦఆͨ͠ϓϩύςΟҎ֎͸ΤϥʔʹͳΔ
27. type Record<K extends keyof any, T> = { [P in K]: T; };
28. type Record<K extends keyof any, T> = { [P in K]: T; }; lLFZPG
    BOZz
    
    lTUSJOH
    c
    OVNCFS
    c
    TZNCPMz
29. Record LFZ໊ͱWBMVFͷܕΛࢦఆͨ͠ΦϒδΣΫτܕ Λ࡞Δ
30. Record
31. Record -BTU
    
    TBUP
    c
    UBOBLB
    ͨΊɺ
    TV[VLJ͸ΤϥʔʹͳΔ
32. Record
33. Record -BTU
    
    TBUP
    c
    TV[VLJ
    c
    UBOBLB
    ͨΊɺ
    UBOBLB͕ແ͍ͱΤϥʔʹͳΔ
34. type Exclude<T, U> = T extends U ? never : T;
35. type Exclude<T, U> = T extends U ? never : T; ࡾ߲ԋࢉࢠͷΑ͏ʹ৚݅ʹΑͬͯܕ͕ܾ·Δ
    5͕6Λܧঝ͍ͯ͠Δ৔߹͸OFWFSɺͦ͏Ͱͳ͍৔߹͸5
    OFWFS͸஋Λฦ͞ͳ͍ܕɻ
36. Exclude ྻڍ͔Βࢦఆͨ͠஋ΛऔΓআ͘
37. Exclude
38. Exclude औΓআ͍ͨ஋Λ୅ೖ͢ΔͱΤϥʔ
39. type Extract<T, U> = T extends U ? T : never;
40. type Extract<T, U> = T extends U ? T : never; 5͕6Λܧঝ͍ͯ͠Δ৔߹͸5ɺ
    ͦ͏Ͱͳ͍৔߹͸OFWFSΛฦ͍ͯ͠Δɻ
    ฦ͢஋͕&YDMVEFͷٯʹͳ͍ͬͯΔ
41. Extract ྻڍͷத͔Βࢦఆͨ͠஋Λநग़
42. Extract
43. Extract நग़ͨ͠஋Ҏ֎Λ୅ೖ͢ΔͱΤϥʔ
44. type NonNullable<T> = T extends null | undefined ? never : T;
45. type NonNullable<T> = T extends null | undefined ? never : T; OVMM·ͨ͸VOEFpOFEΛܧঝ͍ͯ͠ΔܕͰ͋ Ε͹OFWFSɺͦ͏Ͱͳ͍৔߹͸5Λฦ͍ͯ͠Δ
46. NonNullable OVMMͱVOEFpOFEΛऔΓআ͘
47. NonNullable
48. NonNullable OVMM΍VOEFpOFE͸୅ೖͰ͖ͳ͍
49. type Parameters<T extends (...args: any) => any> = T extends (...args: infer P) => any ? P : never;
50. type Parameters<T extends (...args: any) => any> = T extends (...args: infer P) => any ? P : never; JOGFS͸ܕਪ࿦ͨ݁͠ՌΛऔΔ͜ͱ͕Ͱ͖Δ
    ͜ͷ৔߹ؔ਺ͷҾ਺ͷܕΛਪ࿦͍ͯ͠Δɻ
    5͕ؔ਺ܕ ʜBSHT
    JOGFS
    1
    
    BOZͷܧঝͩͬͨ৔߹ɺ ਪ࿦ͨ͠Ҿ਺ͷܕΛฦ͍ͯ͠Δ 5͸ؔ਺ܕͷΈࢦఆͰ͖Δ
51. Parameters ؔ਺ͷҾ਺ͷܕΛλϓϧͰऔΔ
52. Parameters
53. Parameters ؔ਺ͷҾ਺ͷܕʹ߹Θͳ͍ͱΤϥʔ
54. ·ͱΊ • ศརͳܕ͕TypeScriptຊମʹ૊Έࠐ·Ε͍ͯΔ • Conditional TypesͱMapped TypesΛ࢖ͬͯఆٛ͞Ε͍ͯΔ • ࠓ೔঺հ͖͠Εͳ͔ͬͨܕͷఆٛ͸src/lib/es5.d.tsʹ͋ΔͷͰڵ ຯ͕͋Ε͹ݟͯΈ͍ͯͩ͘͞
55. Thanks. @shisama_ @shisama