javascriptの参照と値

Transcript

1. JAVASCRIPT REFERENCES & VALUES

2. Name @brn (⻘野健利) Occupation フロントエンドエンジニア・ネイティブエンジニア Company Cyberagent アドテクスタジオ AI Messenger

   OSS Contributor of V8 About http://info.b6n.ch

3. References and Values ࢀর ஋

4. References and Values ஋ ஋ ࢀর ࢀর

5. References and Values ࢀর͸ؒ઀తʹΦϒδΣΫτΛมߋ͢Δ
   ஋͸௚઀ͦͷΦϒδΣΫτΛมߋ͢Δ

6. References or Values? KBWBTDSJQU͸ࢀরͱ஋ͷ྆ํΛ࢖͏
   ΦϒδΣΫτຖʹͲ͏ѻΘΕΔ͔ܾ·͍ͬͯΔ

7. Javascript object traits ࢀর
   "MM
   WBMVFT
   FYUFOET
   0CKFDU
   ஋
   TUSJOH
   OVNCFS
   CPPMFBO

8. Pass by reference/value const A = const B = ࢀর

   ஋ A = B = ஋

9. Pass by reference const A = {}; const B =

   A; B.x = 1; console.log(A); // { x: 1 }

10. Pass by value const A = 1; const B =

    A; B++; console.log(A); // 1

11. Until here… ͱɺ͜͜·Ͱ͕Α͘ݴΘΕ͍ͯΔ
    ࠓճ͸΋͏ͪΐ͍ਂ۷Γͯ͠Έ͍ͨ

12. Mutable, Immutable KBWBTDSJQUʹ͸
    มߋՄೳͳ஋ͱมߋෆՄೳͳ஋͕͋Δ
    TUSJOH
    OVNCFS
    CPPMFBO͸มߋͰ͖ͳ͍

13. Special cases OVNCFSͱCPPMFBO͸஋౉͠Ͱ͋Δ͜ͱ͕ଟ͍
    ͨͩ͠TUSJOH͸৭ʑͳ޻෉͕͋Δέʔε͕ଟ͍
    7Ͱ͸TUSJOH͸ࢀরͱͳ͍ͬͯΔ

14. String behave like value let A = 'a'; let B

    = A; A += 'b' // Create new instance and assign to self. console.log(A); // 'ab'; console.log(B); // 'a;

15. Immutablity make reference to value *NNVUBCMFͳจࣈྻ͕஋ͷΑ͏ʹৼΔ෣͏͕
    ࣮ࡍʹ͸͢΂ͯࢀরΛ౉͍ͯ͠Δ

16. What is reference? ࢀরͱ͸ͳΜͩΖ͏

17. Pointer ΦϒδΣΫτ͸ੜ੒͞ΕΔͱώʔϓྖҬͱ͍͏ϝ ϞϦʹׂΓ౰ͯΒΕΔ
    ͦͷΦϒδΣΫτΛૢ࡞͢Δ৔߹͸ͦͷϝϞϦྖ ҬΛࢦࣔ͢͠ΞυϨεΛඞཁͱ͢Δ
    ͜Ε͕ϙΠϯλͱݺ͹ΕΔ΋ͷ

18. Pointer is value KTΤϯδϯΛ࣮૷͍ͯ͠Δ$$ ͷੈքͰ͸
    ϙΠϯλͦͷ΋ͷ΋·ͨ஋Ͱ͋Δ
    ͦͷͨΊϙΠϯλͷϙΠϯλΛ࡞ͬͨΓ΋Ͱ͖Δ

19. Reference is value ͔͠͠KBWBTDSJQUͷੈքͰ͸ࢀরͷࢀর͸࡞Εͳ͍
    ͭ·Γࢀর͸ৗʹ஋౉͠ͱͳΔ

20. pass by copy reference ͭ·ΓKBWBTDSJQUͰ͸
    ࢀর ϙΠϯλ Λ஋౉͍ͯ͠͠Δ
    ࢀরͷ஋౉͠
    ͱͳ͍ͬͯΔ

21. Appendix 7಺෦ͷจࣈྻ࣮૷Λ؆୯ʹ

22. String in V8 7Ͱ͸จࣈྻ͕ҎԼͷΫϥεʹ෼͔Ε͍ͯΔ
    4FR0OF#ZUF4USJOH
    4FR5XP#ZUF4USJOH
    $POT4USJOH
    5IJO4USJOH
    4MJDFE4USJOH

23. String in V8 ಛʹTVCTUSJOHΛߦͬͨΓͯ͠
    ৽ͨʹจࣈྻΠϯελϯεΛ࡞੒͢Δ৔߹
    3PQFͱ͍͏ΞϧΰϦζϜΛར༻ͨ͠
    $POT4USJOH͕ར༻͞ΕΔ

24. Rope จࣈྻͷ݁߹͕ߴ଎0 MPH
    O
    ෼ׂ΋ߴ଎0 MPH
    O
    औΓग़͠0 MPH
    O

25. Rope 5PEBZ
    JT
    XF
    BSF
    KBWBTDSJQUFS`T 5PEBZ
    JT XF
    BSF
    KBWBTDSJQUFS`T 3005

26. Rope 5PEBZ
    JT 3005 8F
    BSF KBWBTDSJQUFS`T 53&&

27. Summary ࢀরͱ஋͔Β3PQF·ͰோΊͯΈ·ͨ͠
    ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠