applyMiddleware的参数为什么加展开符？

Question

export default function applyMiddleware(...middlewares) {  return (createStore) => (reducer, preloadedState, enhancer) => {    const store = createStore(reducer, preloadedState, enhancer)    let dispatch = store.dispatch    let chain = []    const middlewareAPI = {      getState: store.getState,      dispatch: (action) => dispatch(action)    }    chain = middlewares.map(middleware => middleware(middlewareAPI))    dispatch = compose(...chain)(store.dispatch)    return {      ...store,      dispatch    }  }}这里参数为什么要用展开符？ 使用的时候传入的是数组，如：const middlewares = [ thunk, logger ]applyMiddleware(...middlewares)那这样函数中 middlewares.map 的 middlewares岂不是 [[thunk, logger]]了么。PS: 奥。。明白了，同时支持applyMiddleware(thunk, logger)和applyMiddleware(...[thunk, logger])两种方式调用。 大家忽略吧

Answer 1

这里用...middlewares，在ES6中叫做[不定参数][1]，和arguments的效果类似，把传入的所有参数，作为一个array赋值给middlewares

例子：

function test(...args) {
   console.log(args); // [1,2,3]}

test(1,2,3)