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いまさら振り返るPromise
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chikoski
July 23, 2017
Technology
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いまさら振り返るPromise
chikoski
July 23, 2017
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Transcript
いまさら振り返るPromise N.Shimizu (
[email protected]
)
Promise: いずれされる処理を表すオブジェクト https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Promise 1SPNJTF UIFO GVM'JMMFE UIFO SFKFDUFE DBUDI
SFKFDUFE 1SPNJTF Pending Fulfill Reject Return Return
Promise chain GFUDI IUUQTFYBNQMFDPNFOEQPJOUTPNFBDUJPO UIFO SFTQPOTFSFTQPOTFKTPO FSSOPUJGZ&SSPS FSS
UIFO EBUBEBUBMFOHUI EBUB1SPNJTFSFKFDU OPEBUB UIFO EBUBSFOEFS%BUB EBUB FSSOPUJGZ/P%BUB
処理を始めるところと、結果を利用するところを分けられる EP4PNFUIJOH QBSBN SFTQPOTF\ JG SFTQPOTFFSS \ SFUVSOIBOEMF&SSPS SFTQPOTFFSS
^ EP" EP# EP$ EP% DPOTVNF SFTQPOTFSFTVMU ^ DPOTUQEP4PNFUJOH QBSBN EP" EP# EP$ EP% QUIFO DPOTVNF DBUDI IBOEMF&SSPS
Promise: 条件分岐の一種 https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Promise 1SPNJTF UIFO GVM'JMMFE UIFO SFKFDUFE DBUDI
SFKFDUFE 1SPNJTF Pending Fulfill Reject Return Return
直列化 UFTU" UIFO UFTU# UIFO TVDDFTT DBUDI GBJM
<UFTU" UFTU#> SFEVDF QSP GVOD QSPUIFO GVOD UIFO TVDDFTT DBUDI GBJM 1SPNJTFBMM <UFTU" UFTU# > UIFO TVDDFTT DBUDI GBJM 㛈ᏁҶ⼊ҿӶӔҮ UFTU" UFTU# TVDDFTT GBJM F T T F
並列化 UFTU" DBUDI UFTU# UIFO TVDDFTT DBUDI GBJM
1SPNJTFSBDF <UFTU" UFTU# > UIFO TVDDFTT DBUDI GBJM 㛈ᏁҶ⼊ҿӶӔҮ UFTU" UFTU# TVDDFTT GBJM F T T F
エラー処理を本筋と分けて実装できる MFUSFTVMUEP4PNFUIJOH JG SFTVMUOVMM \ SFTVMUEFGBVMU7BMVF ^ DPOTVNF
SFTVMU EP4PNFUIJOH DBUDI FSSEFGBVMU7BMVF UIFO DPOTVNF
Promise非対応のPromise対応にするには GVODUJPOBEE B C \ SFUVSOB C ^ GVODUJPOQSPNJTFE"EE B
C \ SFUVSO1SPNJTFSFTPMWF B C ^ QSPNJTFE"EE UIFO JDPOTPMFMPH
Promise非対応のPromise対応にするには GVODUJPOBEE B C \ JG B]]C \ UISPXOFX&SSPS *OWBMJEQBSBNFUFS
^ SFUVSOB C ^ GVODUJPOQSPNJTFE"EE B C \ USZ\SFUVSO1SPNJTFSFTPMWF BEE B C ^ DBUDIFSS\SFUVSO1SPNJTFSFKFDU FSS ^ ^
Promise非対応のPromise対応にするには DPOTUGTSFRVJSF GT GVODUJPOSFBE GJMF \ SFUVSOOFX1SPNJTF SFTPMWF SFKFDU
\ GTSFBE'JMF GJMF FSS EBUB \ FSS SFTPMWF FSS SFKFDU EBUB ^ ^ ^
Promise非対応のPromise対応にするには GVODUJPOBEE0OF OVNCFST \ DPOTUSFTVMU<> GPS DPOTUOVNPGOVNCFST \ SFTVMUQVTI OVN
^ ^ GVODUJPOQSPNJTFE"EE0OF OVNCFST \ SFUVSO1SPNJTFBMM OVNCFSTNBQ J1SPNJTFSFTPMWF J ^
Anti-pattern: ネストしたPromise EP" UIFO SFTVMU"\ EP# UIFO SFTVMU#DPOTVNF SFTVMU" SFTTVMU#
^ 1SPNJTFBMM <EP" EP# > UIFO SFTVMUTDPOTVNF SFTVMUT<> SFTVMU<> http://taoofcode.net/promise-anti-patterns/
Anti-pattern: 続かないチェーン GVODUJPOEP4PNFUIJOH \ DPOTUQSPNJTFEP" QSPNJTFUIFO SFTVMUDPOTVNF SFTVMU
SFUVSOQSPNJTF ^ GVODUJPOEP4PNFUIJOH \ SFUVSOEP" UIFO SFTVMUDPOTVNF SFTVMU ^ http://taoofcode.net/promise-anti-patterns/