看到一個項目中引入的是 import fetch from 'isomorphic-fetch';然后在定義action—type時，寫的：export const FETCH_RUNS = 'FETCH_RUNS';export const FETCH_RUNS_PENDING = 'FETCH_RUNS_PENDING';export const FETCH_RUNS_FULFILLED = 'FETCH_RUNS_FULFILLED';export const FETCH_RUNS_REJECTED = 'FETCH_RUNS_REJECTED';加了三種狀態pending，fulfilled，rejectedaction中只寫了type: FETCH_RUNS的：import {fetchRuns} from '../../services/RunService';const fetchRunsAction = (req) => ({  type: FETCH_RUNS,  payload: fetchRuns(req)});export {  fetchRunsAction as fetchRuns}而在reducer中對三種狀態的action都做了處理：import {  FETCH_RUNS_FULFILLED,  FETCH_RUNS_PENDING,  FETCH_RUNS_REJECTED} from '../actions/runActions';// INITIALIZE STATEconst initialState = {  runs: null,  fetched: false,  fetching: false,  failed: false};// REDUCERexport const FetchRunsReducer = (state = initialState, action) => {  switch (action.type) {    case FETCH_RUNS_PENDING:      return {        ...state,        fetching: true,        fetched: false,        failed: false      };    case FETCH_RUNS_FULFILLED:      return {        ...state,        runs: action.payload,        fetching: false,        fetched: true,        failed: false      };    case FETCH_RUNS_REJECTED:      return {        ...state,        runs: null,        fetching: false,        fetched: false,        failed: true      };    default:      return state;  }};在組件中：...const mapStateToProps = state => {  const {fetched, fetching, runs} = state.runs;  return {    fetched,    fetching,    runs  };};const mapDispatchToProps = dispatch => {  return bindActionCreators({fetchRuns}, dispatch);};現在我的疑惑點在——什么時候觸發了FETCH_RUNS_PENDING，FETCH_RUNS_FULFILLED，FETCH_RUNS_REJECTED這三個狀態；在promise是有三個狀態，自動觸發，但是程序如何跳到代碼中寫的這三個action名字FETCH_RUNS_PENDING，FETCH_RUNS_FULFILLED，FETCH_RUNS_REJECTED；我想是不是某個封裝的地方給action名字自動后面添加了PENDING、FULFILLED，REJECTED然后在觸發此action的時候后自動觸發這幾個狀態的action。那么請問在哪個里面進行了封裝呢？代碼中沒有找到啊，是不是react，redux某個里面封裝的？求助