ES6 Promises: Patterns and Anti-Patterns
When I first got started with NodeJS a few years ago, I was mortified by what is now affectionately known as “callback hellâ€. Fortunately, here in 2017, NodeJS has adopted the latest and greatest JavaScript features, and since v4 has supported Promises. But while Promises make code more concise and readable, they can be a bit daunting to those who are only familiar with callbacks. Here I’ll lay ou
Passing data between Promise callbacks
In Promise-based code, there are usually many callbacks, each one having a separate scope for variables. What if you want to share data between those callbacks? This blog post describes techniques for doing so. The problem  # The following code illustrates a common problem with Promise callbacks: The variable connection (line A) exists in one scope, but needs to be accessed in other scopes (line B
Fetch ã®ä¸æ–㨠Promise ã®ã‚ャンセル方法ã®æ¨™æº–化 | blog.jxck.io
Intro XHR ã‹ã‚‰ fetch() ã«ç©æ¥µçš„ã«ç§»è¡Œã—ã¥ã‚‰ã‹ã£ãŸæœ€å¤§ã®ãƒŸãƒƒã‚·ãƒ³ã‚°ãƒ”ースã¨ã—ã¦ã€ä¸æ–ã§ããªã„ã¨ã„ã†å•é¡ŒãŒã‚ã£ãŸã€‚ ã“ã‚Œã¯ã€ fetch() ãŒé¸ã‚“ã Promise ベースã®ã‚¤ãƒ³ã‚¿ãƒ•ã‚§ãƒ¼ã‚¹ã«ãŠã„ã¦ã€ã‚ャンセルをã©ã†ã™ã‚‹ã‹ã¨ã„ã†è°è«–ã¨çµ¡ã¿ã€é•·ã決ç€ãŒä»˜ã‹ãšã«ã„ãŸå•é¡Œã§ã‚る。 最近ã€ã‚„ã£ã¨è©±ãŒå‰é€²ã—ãŸã®ã§ã€ã“ã“ã¾ã§ã®çµŒéŽã‚’解説ã™ã‚‹ã€‚ Fetch ã®ãƒŸãƒƒã‚·ãƒ³ã‚°ãƒ”ース fetch() ã¯ã€ãƒ–ラウザãŒç™ºè¡Œã™ã‚‹ãƒªã‚¯ã‚¨ã‚¹ãƒˆã¨ã€å–å¾—ã™ã‚‹ãƒ¬ã‚¹ãƒãƒ³ã‚¹ã‚’扱ã†ä½Žãƒ¬ãƒ™ãƒ«ãªã‚¤ãƒ³ã‚¿ãƒ•ã‚§ãƒ¼ã‚¹ã¨ã—ã¦ç–定ãŒå§‹ã¾ã£ãŸã€‚ DOM ã® API ㌠Promise ベースã«ç§»è¡Œã—ã¤ã¤ã‚ã‚‹æµã‚Œã‚’æ±²ã¿ã€ fetch() ã‚‚ã¾ãŸ Promise ã‚’è¿”ã™é–¢æ•°ä¸€ç™ºã‚¹ã‚¿ã‚¤ãƒ«ã«ãªã£ãŸã€‚ クラスã‹ã‚‰ã‚¤ãƒ³ã‚¹ã‚¿ãƒ³ã‚¹ã‚’生æˆã—メソッドを呼㶠XHR スタイルã§ã¯ã€ã‚¤ãƒ³ã‚¹ã‚¿ãƒ³ã‚¹ã‚’å†åˆ©ç”¨ã—ãŸå ´åˆã®æŒ™å‹•ãªã©ã‚’å«ã‚ã€ã‚ªãƒ–ジェクトã®ãƒ©ã‚¤ãƒ•ã‚µã‚¤ã‚¯ãƒ«ã‚’
ã‚ãªãŸãŒèªã‚€ã¹ãJavaScript Promises | JSer.info
ã¯ã˜ã‚ã« ã“ã®è¨˜äº‹ã¯ã€ JavaScript/ES6 promisesã«ã¤ã„ã¦ã‚’ç†è§£ã™ã‚‹ãŸã‚ã«èªã‚“ã æ–¹ãŒã‚ˆã„ã¨æ€ã‚れる記事やスライドç‰ã‚’紹介ã—ã¦ã„ã¾ã™ã€‚ Promisesã‚„Deferredã¨ã„ã£ãŸè¨€è‘‰ã‚’éžåŒæœŸå‡¦ç†ã®è©±ãªã©ã§èžã„ãŸäº‹ãŒã‚ã‚‹ã‹ã‚‚ã—ã‚Œã¾ã›ã‚“ãŒã€ ç¾åœ¨Promisesã¯æ¬¡ã®ECMAScriptã®è¨€èªžä»•æ§˜ã¨ã—ã¦ç–定ãŒé€²ã‚られã¦ã„ã¾ã™ã€‚ ECMAScript Language Specification ECMA-262 6th Edition – DRAFT domenic/promises-unwrapping ã¾ã ES6ã¯ç–定段階ã§ã™ãŒã€æ—¢ã«Promisesã«ã¤ã„ã¦ã¯polyfillã¨ã—ã¦åˆ©ç”¨ã§ãるライブラリç‰ã‚‚ã‚ã‚Šã€ã¾ãŸä»–ã®ãƒ©ã‚¤ãƒ–ラリ内ã§ã‚‚jQuery.Deferred()ã‚„Angularã®$qç‰é¡žä¼¼ã™ã‚‹å®Ÿè£…ãŒå˜åœ¨ã—ã¾ã™ã€‚ ãã®ãŸã‚ã€Generatorsç‰ã«æ¯”ã¹ã‚‹ã¨ä»Šã™ã使ãˆã‚‹
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