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Why Redux-Observable?
This document discusses the benefits of using Redux-Observable over Redux-Thunk for handling asynchronous logic in Redux applications. It begins by showing an example of how a search functionality would be implemented using Redux-Thunk, which requires additional logic for canceling requests. It then demonstrates how the same search functionality can be implemented more concisely and readably using Redux-Observable through the use of Epics. Overall, the document argues that Redux-Observable provides a simpler and more efficient way to solve common asynchronous problems compared to Redux-Thunk.
Why Redux-Observable?
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- 9. PM 跟你說：網站要做 搜尋功能 9 ‣ 顯⽰示搜尋結果 ‣ 記錄關鍵字 History
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- 11. 搜尋功能 你可能會這樣寫... 11 let controller; export constsearch = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); };
- 12. 搜尋功能 搜尋關鍵字必須有值， 才執⾏行行 request 12 let controller; exportconst search = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); }
- 13. 搜尋功能 回傳搜尋資料之前， 顯⽰示 Loading 動畫 13 letcontroller; export const search = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST }); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal,
- 14. 搜尋功能 GET API，取得搜尋資料 14 dispatch({ type:SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); };
- 15. 搜尋功能 觸發另外⼀一個 action 顯⽰示搜尋結果 15 dispatch({ type:SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); };
- 16. 搜尋功能 dispatch({ type: SEARCH_REQUEST}); if(controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); }; 變更更網址 16
- 17. 搜尋功能 dispatch({ type: SEARCH_REQUEST}); if(controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); }; 傳入關鍵字，記錄 History 17
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- 21. 搜尋功能 宣告 controller 變數 21 letcontroller; export const search = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); }
- 22. 搜尋功能 新增 controller 提供取消 request的⽅方法 22 dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?keyword=${keyword}&lim signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); };
- 23. 搜尋功能 將舊的 request 取消， 執⾏行行新的request 23 dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?keyword=${keyword}&lim signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); };
- 24. 搜尋功能 使⽤用 redux-thunk… 24 let controller; exportconst search = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?keyword=${keyword}&limit=20`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); };
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- 26. 26 redux-thunk redux-observable let controller; exportconst search = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); }; export const searchEpic = action$ !=> action$ .ofType(SEARCH_REQUEST) .filter(action !=> action.payload) .switchMap(getSearchResult) .mergeMap(res !=> Observable.of( receiveSearchResult(res.data), push(`/search/${res.keyword}`), addSearchHistory(res.keyword) ) );
- 27. 27 let controller; export constsearch = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); }; export const searchEpic = action$ !=> action$ .ofType(SEARCH_REQUEST) .filter(action !=> action.payload) .switchMap(getSearchResult) .mergeMap(res !=> Observable.of( receiveSearchResult(res.data), push(`/search/${res.keyword}`), addSearchHistory(res.keyword) ) ); 25⾏行行程式碼 12⾏行行程式碼 程式碼 少了了 1/2 redux-observable ⼤大約
- 28. 28 let controller; export constsearch = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); }; export const searchEpic = action$ !=> action$ .ofType(SEARCH_REQUEST) .filter(action !=> action.payload) .switchMap(getSearchResult) .mergeMap(res !=> Observable.of( receiveSearchResult(res.data), push(`/search/${res.keyword}`), addSearchHistory(res.keyword) ) ); 有 if 判斷 沒有 if 判斷 程式碼 容易易閱讀 redux-observable 比較
- 29. 29 let controller; export constsearch = keyword !=> dispatch !=> { if (!keyword) { return; } dispatch({ type: SEARCH_REQUEST}); if (controller) { controller.abort(); } controller = new AbortController(); return fetch(`/search?k=${keyword}`, { signal: controller.signal, }).then(res !=> { dispatch(receiveSearchResult(res)); dispatch(push(`/search/${keyword}`)); dispatch(addKeywordHistory(keyword)); controller = undefined; }); }; export const searchEpic = action$ !=> action$ .ofType(SEARCH_REQUEST) .filter(action !=> action.payload) .switchMap(getSearchResult) .mergeMap(res !=> Observable.of( receiveSearchResult(res.data), push(`/search/${res.keyword}`), addSearchHistory(res.keyword) ) ); 只⽀支援 firefox 57 版 只有 IE 10 以下不⽀支援 有效率的完成功能 redux-observable
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- 32. RxJS 5-based middlewarefor Redux 32
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- 37. 37 Store dispatch epic epic epicepicepic redux-observable Reducer Action State
- 38. 38 Store dispatch epic epic epicepicepic redux-observable Reducer Action State
- 39. 39 Store dispatch epic epic epicepicepic redux-observable Reducer Action State
- 40. export const openToastEpic= action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); }; Epic 40
- 41. export const openToastEpic= action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); }; Epic 41
- 42. export const openToastEpic= action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); }; Epic 42
- 43. 43 epic epic epicepicepic
- 44. epic epic epicepicepic rootEpic 44
- 45. rootEpic.js 45 import { combineEpics} from 'redux-observable'; import { openToastEpic } from './toastStatus.js'; import { checkEmailEpic } from './emailCheckStatus.js'; import { searchEpic } from './search.js'; import { getArticlesEpic } from './articles.js'; export default combineEpics( openToastEpic, checkEmailEpic, searchEpic, getArticlesEpic );
- 46. index.js 46 … const store =createStore( reducer, applyMiddleware(createEpicMiddleware(rootEpics)) ); … Store Middleware Reducer
- 47. index.js 47 … const store =createStore( reducer, applyMiddleware(createEpicMiddleware(rootEpics)) ); … Store Middleware Reducer
- 48. index.js 48 … const store =createStore( reducer, applyMiddleware(createEpicMiddleware(rootEpics)) ); … Store Middleware Reducer
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- 54. 訊息通知 按下按鈕 觸發 action creator 54 <buttononClick={openToast}>確定#</button>
- 55. 訊息通知 建立 action creator和 epic 55 export const openToast = () !=> ({ type: OPEN_TOAST, }); export const openToastEpic = action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); };
- 56. 訊息通知 傳入 action observable 56 exportconst openToastEpic = action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); };
- 57. 訊息通知 過濾出對應的 action type 57 exportconst openToastEpic = action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); };
- 58. 訊息通知 delay 3 秒 58 exportconst openToastEpic = action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); };
- 59. 訊息通知 觸發關閉 Toast 的action 59 export const openToastEpic = action$ !=> { return action$ .ofType(OPEN_TOAST) .delay(3000) .mapTo({ type: CLOSE_TOAST }); };
- 60. 訊息通知 到 reducer、更更新 state 改變store 60 export default function toastStatus(state = false, action) { switch (action.type) { case OPEN_TOAST: return true; case CLOSE_TOAST: return false; default: return state; } }
- 61. 訊息通知 到 reducer、更更新 state 改變store 61 export default function toastStatus(state = false, action) { switch (action.type) { case OPEN_TOAST: return true; case CLOSE_TOAST: return false; default: return state; } }
- 62. 訊息通知 UI 發⽣生改變 62 <div className={classNames('toast',{ show })}> <p>儲存成功！#</p> #</div>
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- 69. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 過濾出對應的 action type 69
- 70. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 觸發後，靜置500毫秒 70
- 71. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 觸發後，靜置500毫秒才做驗證 71 通常⽤用在輸入框 靜置⼀一段時間才觸發 debounceTime
- 72. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 接收最新的 request， 舊的 request 都取消 72
- 73. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 取最新的 request， 舊的 request 都取消 73 取消舊的 request，執⾏行行新的 request switchMap 情境1: 表單即時驗證 情境2: Autocomplete 的輸入框
- 74. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 獲取 Email 狀狀態 74
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- 76. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; Email 格式正確才發 request 76
- 77. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 觸發後，靜置500毫秒才做驗證 77 快速輕鬆的完成功能 不需要會 RxJS，就可以使⽤用 operator
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- 80. 過濾出對應的 action type 80 exportconst getArticlesEpic = action$ !=> { return action$ .ofType(GET_ARTICLES) .exhaustMap(getArticlesAPI) .map(receiveArticles); }; 載入更更多⽂文章
- 81. 取原本送出的 request， 新的 request都取消 81 export const getArticlesEpic = action$ !=> { return action$ .ofType(GET_ARTICLES) .exhaustMap(getArticlesAPI) .map(receiveArticles); }; 載入更更多⽂文章
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- 84. 無限滾動⽂文章 export const getArticlesEpic= action$ !=> { return action$ .ofType(GET_ARTICLES) .exhaustMap(getArticlesAPI) .map(receiveArticles); }; 取原本送出的 request， 新的 request 都取消 84
- 85. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 取最新的 request， 舊的 request 都取消 85 取原本送出的 request，新的 request 都取消 exhaustMap 情境1: 看更更多⽂文章 情境2: 上傳檔案
- 86. export const getArticlesEpic= actions !=> { return actions .ofType(GET_ARTICLES) .throttleTime(100) .exhaustMap(getArticlesAPI) .map(receiveArticles); }; 無限滾動⽂文章 throttle 100 毫秒 才送 request 86
- 87. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 觸發後，靜置500毫秒才做驗證 87 通常⽤用在連續性⾏行行為 throttleTime 情境1: 滾動事件 情境2: 拖拉事件 避免⾼高頻率觸發
- 88. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 觸發後，靜置500毫秒才做驗證 88 重⽤用性與可讀性提昇 組合使⽤用 operator
- 89. Email 即時驗證 export constcheckEmailEpic = actions !=> { return actions .ofType(CHECK_EMAIL) .debounceTime(500) .filter(validateEmail) .switchMap(checkEmailIsUnique) .map(receiveEmailStatus); }; 觸發後，靜置500毫秒才做驗證 89 優雅的解決非同步問題 簡單使⽤用 operator
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- 93. 93 13 Jul 2015 redux-thunkredux-saga 3 Dec 2015 redux-observable 21 Apr 2016 redux-cycle 3 Dec 2016 2017/10/23 Redux middlewares
- 94. redux-thunk redux-observable 94 export constopenPopup = () !=> dispatch !=> { dispatch({ type: OPEN_POPUP, }); setTimeout(() !=> { dispatch({ type: CLOSE_POPUP, }); }, 3000); }; export const openPopupEpic = action$ !=> { return action$ .ofType(OPEN_POPUP) .delay(3000) .mapTo({ type: CLOSE_POPUP }); };
- 95. redux-thunk •容易易上⼿手 •程式碼冗長 •不易易閱讀 •難以維護 95 export const openPopup= () !=> dispatch !=> { dispatch({ type: OPEN_POPUP, }); setTimeout(() !=> { dispatch({ type: CLOSE_POPUP, }); }, 3000); };
- 96. redux-saga redux-observable 96 export function*openPopupAsync () { yield call(delay, 3000) yield put({ type: 'CLOSE_POPUP' }) } export function* watchOpenPopupAsync () { yield takeEvery('OPEN_POPUP', openPopupAsync) } export const openPopupEpic = action$ !=> { return action$ .ofType(OPEN_POPUP) .delay(3000) .mapTo({ type: CLOSE_POPUP }); };
- 97. redux-saga •技術不能轉移 •依賴 syntax (Generator) 97 exportfunction* openPopupAsync () { yield call(delay, 3000) yield put({ type: 'CLOSE_POPUP' }) } export function* watchOpenPopupAsync () { yield takeEvery('OPEN_POPUP', openPopupAsync) } •可以處理理較複雜的非同步問題 •星星數較多，使⽤用社群較⼤大
- 98. redux-cycles redux-observable 98 export constopenPopupEpic = action$ !=> { return action$ .ofType(OPEN_POPUP) .delay(3000) .mapTo({ type: CLOSE_POPUP }); }; function openPopup (sources) { const openPopup$ = sources.ACTION .filter(action !=> action.type &&=== OPEN_POPUP) .delay(3000) .mapTo({ type: CLOSE_POPUP }); return { ACTION: openPopup$ } }
- 99. redux-cycles redux-observable 99 function fetchUserData(sources){ const request$ = sources.ACTION .filter(action !=> action.type &&=== FETCH_USER) .map(action !=> ({ url: `${API_URL}users/`, category: 'users', })); const action$ = sources.HTTP .select('users') .flatten() .map(fetchUserFulfilled); return { ACTION: action$, HTTP: request$, }; } const fetchUserDataEpic = action$ !=> action$ .ofType(FETCH_USER) .mergeMap(action !=> ajax.getJSON(`${API_URL}users/`) .map(fetchUserFulfilled) );
- 100. redux-cycle •社群⼈人數較少 •過度封裝? 100 function fetchUserData(sources) { constrequest$ = sources.ACTION .filter(action !=> action.type &&=== FETCH_USER) .map(action !=> ({ url: `${API_URL}users/`, category: 'users', })); const action$ = sources.HTTP .select('users') .flatten() .map(fetchUserFulfilled); return { ACTION: action$, HTTP: request$, }; } •可以處理理較複雜的 非同步問題
- 101. 101 redux-thunk redux-saga redux-cycleredux-observable 程式碼簡潔 處理複雜的⾮同步情境 技術可轉移 Why Redux-Observable?
- 102. 102 redux-thunk redux-saga redux-cycleredux-observable 程式碼簡潔 處理複雜的⾮同步情境 技術可轉移 Why Redux-Observable?
- 103. （你應該學習 Observable 的原因） 103 技術可轉移 RxJava RxPHP 將成為ECMAScript 標準 Stage1 前端框架都有 Observable Redux-Observable vue-rx Angular2 之後RxSwift Why Redux-Observable?
- 104. 104 ‣ 程式碼更更簡潔 ‣ 可讀性更更⾼高 ‣容易易寫測試 ‣ 更更快速完成功能 Why Redux-Observable?
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- 109. Reference ‣ https://redux-observable.js.org/ ‣ https://github.com/redux-observable/redux-observable ‣http://reactivex.io/languages.html ‣ https://github.com/reactjs/redux/issues/1461#issuecomment-190165193 ‣ https://developer.mozilla.org/en-US/docs/Web/API/AbortController/abort ‣ https://twitter.com/dan_abramov/status/816244945015160832 109
- 110. Image Credit ‣ http://oreilly-generator.com/ ‣http://renzhou.tw/yinwubrother-textmaker/ ‣ https://www.flaticon.com/packs/emoji-6 ‣ https://www.flaticon.com/packs/design-35 110
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