Advanced built-in types / #kansaits 1

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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; }; lLFZPGBOZzlTUSJOHcOVNCFScTZNCPMz

29. Record LFZ໊ͱWBMVFͷܕΛࢦఆͨ͠ΦϒδΣΫτܕ Λ࡞Δ

30. Record

31. Record -BTUTBUPcUBOBLBͨΊɺ TV[VLJ͸ΤϥʔʹͳΔ

32. Record

33. Record -BTUTBUPcTV[VLJcUBOBLBͨΊɺ 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 ʜBSHTJOGFS1 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