javascriptの参照と値

javascriptの参照渡しと値渡しについて

Transcript

1. JAVASCRIPT
   REFERENCES & VALUES
   

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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
   

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3. References and Values
   ࢀর ஋
   

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4. References and Values
   ஋
   ஋
   ࢀর
   ࢀর
   

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

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

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7. Javascript object traits
   ࢀর
   "MMWBMVFTFYUFOET0CKFDU
   ஋
   TUSJOH OVNCFS CPPMFBO
   

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

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9. Pass by reference
   const A = {};
   const B = A;
   B.x = 1;
   console.log(A);
   // { x: 1 }
   

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10. Pass by value
    const A = 1;
    const B = A;
    B++;
    console.log(A);
    // 1
    

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

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

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

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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;
    

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

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16. What is reference?
    ࢀরͱ͸ͳΜͩΖ͏
    

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

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

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

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

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21. Appendix
    7಺෦ͷจࣈྻ࣮૷Λ؆୯ʹ
    

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

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

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24. Rope
    จࣈྻͷ݁߹͕ߴ଎0 MPHO
    
    ෼ׂ΋ߴ଎0 MPHO
    
    औΓग़͠0 MPHO
    
    

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25. Rope
    5PEBZJTXFBSFKBWBTDSJQUFS`T
    5PEBZJT XFBSFKBWBTDSJQUFS`T
    3005
    

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26. Rope
    5PEBZJT
    3005
    8FBSF KBWBTDSJQUFS`T
    53&&
    

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27. Summary
    ࢀরͱ஋͔Β3PQF·ͰோΊͯΈ·ͨ͠
    ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠
    

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