Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
javascriptの参照と値
Search
Taketoshi Aono(青野健利 a.k.a brn)
October 23, 2018
2
850
javascriptの参照と値
javascriptの参照渡しと値渡しについて
Taketoshi Aono(青野健利 a.k.a brn)
October 23, 2018
Tweet
Share
More Decks by Taketoshi Aono(青野健利 a.k.a brn)
See All by Taketoshi Aono(青野健利 a.k.a brn)
document.write再考
brn
6
3k
Parsing Javascript
brn
14
9.3k
JSON & Object Tips
brn
1
500
CA 1Day Youth Bootcamp for Frontend LT
brn
0
960
Modern TypeScript
brn
2
820
javascript - behind the scene
brn
3
750
tc39 proposals
brn
0
890
プロダクト開発とTypeScript
brn
8
2.9k
React-Springでリッチなアニメーション
brn
1
710
Featured
See All Featured
Save Time (by Creating Custom Rails Generators)
garrettdimon
PRO
32
1.4k
Speed Design
sergeychernyshev
32
1.1k
Rails Girls Zürich Keynote
gr2m
95
14k
Mobile First: as difficult as doing things right
swwweet
223
9.9k
Designing for humans not robots
tammielis
253
25k
Optimizing for Happiness
mojombo
379
70k
How to Create Impact in a Changing Tech Landscape [PerfNow 2023]
tammyeverts
53
2.9k
The Cult of Friendly URLs
andyhume
79
6.5k
Music & Morning Musume
bryan
46
6.7k
Distributed Sagas: A Protocol for Coordinating Microservices
caitiem20
333
22k
Improving Core Web Vitals using Speculation Rules API
sergeychernyshev
18
1.1k
[Rails World 2023 - Day 1 Closing Keynote] - The Magic of Rails
eileencodes
36
2.5k
Transcript
JAVASCRIPT REFERENCES & VALUES
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
References and Values ࢀর
References and Values ࢀর ࢀর
References and Values ࢀরؒతʹΦϒδΣΫτΛมߋ͢Δ ͦͷΦϒδΣΫτΛมߋ͢Δ
References or Values? KBWBTDSJQUࢀরͱͷ྆ํΛ͏ ΦϒδΣΫτຖʹͲ͏ѻΘΕΔ͔ܾ·͍ͬͯΔ
Javascript object traits ࢀর "MMWBMVFTFYUFOET0CKFDU TUSJOH OVNCFS CPPMFBO
Pass by reference/value const A = const B = ࢀর
A = B =
Pass by reference const A = {}; const B =
A; B.x = 1; console.log(A); // { x: 1 }
Pass by value const A = 1; const B =
A; B++; console.log(A); // 1
Until here… ͱɺ͜͜·Ͱ͕Α͘ݴΘΕ͍ͯΔ ࠓճ͏ͪΐ͍ਂ۷Γͯ͠Έ͍ͨ
Mutable, Immutable KBWBTDSJQUʹ มߋՄೳͳͱมߋෆՄೳͳ͕͋Δ TUSJOH OVNCFS CPPMFBOมߋͰ͖ͳ͍
Special cases OVNCFSͱCPPMFBO͠Ͱ͋Δ͜ͱ͕ଟ͍ ͨͩ͠TUSJOH৭ʑͳ͕͋Δέʔε͕ଟ͍ 7ͰTUSJOHࢀরͱͳ͍ͬͯΔ
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;
Immutablity make reference to value *NNVUBCMFͳจࣈྻ͕ͷΑ͏ʹৼΔ͏͕ ࣮ࡍʹͯ͢ࢀরΛ͍ͯ͠Δ
What is reference? ࢀরͱͳΜͩΖ͏
Pointer ΦϒδΣΫτੜ͞ΕΔͱώʔϓྖҬͱ͍͏ϝ ϞϦʹׂΓͯΒΕΔ ͦͷΦϒδΣΫτΛૢ࡞͢Δ߹ͦͷϝϞϦྖ ҬΛࢦࣔ͢͠ΞυϨεΛඞཁͱ͢Δ ͜Ε͕ϙΠϯλͱݺΕΔͷ
Pointer is value KTΤϯδϯΛ࣮͍ͯ͠Δ$$ ͷੈքͰ ϙΠϯλͦͷͷ·ͨͰ͋Δ ͦͷͨΊϙΠϯλͷϙΠϯλΛ࡞ͬͨΓͰ͖Δ
Reference is value ͔͠͠KBWBTDSJQUͷੈքͰࢀরͷࢀর࡞Εͳ͍ ͭ·Γࢀরৗʹ͠ͱͳΔ
pass by copy reference ͭ·ΓKBWBTDSJQUͰ ࢀর ϙΠϯλ Λ͍ͯ͠͠Δ ࢀরͷ͠ͱͳ͍ͬͯΔ
Appendix 7෦ͷจࣈྻ࣮Λ؆୯ʹ
String in V8 7Ͱจࣈྻ͕ҎԼͷΫϥεʹ͔Ε͍ͯΔ 4FR0OF#ZUF4USJOH 4FR5XP#ZUF4USJOH $POT4USJOH 5IJO4USJOH 4MJDFE4USJOH
String in V8 ಛʹTVCTUSJOHΛߦͬͨΓͯ͠ ৽ͨʹจࣈྻΠϯελϯεΛ࡞͢Δ߹ 3PQFͱ͍͏ΞϧΰϦζϜΛར༻ͨ͠ $POT4USJOH͕ར༻͞ΕΔ
Rope จࣈྻͷ݁߹͕ߴ0 MPHO ׂߴ0 MPHO औΓग़͠0 MPHO
Rope 5PEBZJTXFBSFKBWBTDSJQUFS`T 5PEBZJT XFBSFKBWBTDSJQUFS`T 3005
Rope 5PEBZJT 3005 8FBSF KBWBTDSJQUFS`T 53&&
Summary ࢀরͱ͔Β3PQF·ͰோΊͯΈ·ͨ͠ ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠