下面的代码会输出:
A middleware1 开始
C middleware2 开始
E middleware3 开始
======= G =======
F middleware3 结束
D middleware2 结束
B middleware1 结束
首先 middleware1, middleware2, middleware3 都先串联对象 middlewareAPI,
var middlewareAPI = {
getState: store.getState,
dispatch: (action) => dispatch(action)
}
middlewares.map(middleware => middleware(middlewareAPI));
然后内部是这样执行的 A1( A2( A3(store.dispatch) ) )( actionCreate() ),
A3的next 是store.dispatch, A2的next 是A3最里层的函数, A1的next 是A2里最里层的函数。
var A1 = function(next) {
return function(action) {
console.log(‘A middleware1 开始‘);
next(action)
console.log(‘B middleware1 结束‘);
};
};
var A2 = function(next) {
return function(action) {
console.log(‘C middleware2 开始‘);
next(action)
console.log(‘D middleware2 结束‘);
};
};
var A3 = function(next) {
return function(action) {
console.log(‘E middleware3 开始‘);
next(action)
console.log(‘F middleware3 结束‘);
};
};
<!DOCTYPE html>
<html>
<head>
<script src="//cdn.bootcss.com/redux/3.5.2/redux.min.js"></script>
</head>
<body>
<script>
function middleware1(store) {
return function(next) {
return function(action) {
console.log(‘A middleware1 开始‘);
next(action)
console.log(‘B middleware1 结束‘);
};
};
}
function middleware2(store) {
return function(next) {
return function(action) {
console.log(‘C middleware2 开始‘);
next(action)
console.log(‘D middleware2 结束‘);
};
};
}
function middleware3(store) {
return function(next) {
return function(action) {
console.log(‘E middleware3 开始‘);
next(action)
console.log(‘F middleware3 结束‘);
};
};
}
function reducer(state, action) {
if (action.type === ‘MIDDLEWARE_TEST‘) {
console.log(‘======= G =======‘);
}
return {};
}
var store = Redux.createStore(
reducer,
Redux.applyMiddleware(
middleware1,
middleware2,
middleware3
)
);
store.dispatch({ type: ‘MIDDLEWARE_TEST‘ });
</script>
</body>
</html>
时间： 2024-07-30 10:19:23