使用vue技术栈，作为一个前端架构师是必须掌握这些知识点的

function sum(a, b) {
  return a + b;
}

function sum(a: number, b:number) {
  return a + b;
}

export function renderList (
  val: any,
  render: (
    val: any,
    keyOrIndex: string | number,
    index?: number
  ) => VNode
): ?Array<VNode>{
...
}

export function defineReactive (
  obj: Object,
  key: string,
  val: any,
  customSetter?: ?Function,
  shallow?: boolean
) {
  .....
  Object.defineProperty(obj, key, {
    enumerable: true,
    configurable: true,
    get: function reactiveGetter () {
      const value = getter ? getter.call(obj) : val
      if (Dep.target) {
        dep.depend()
        if (childOb) {
          childOb.dep.depend()
          if (Array.isArray(value)) {
            dependArray(value)
          }
        }
      }
      return value
    },
    set: function reactiveSetter (newVal) {
      const value = getter ? getter.call(obj) : val
      /* eslint-disable no-self-compare */
      if (newVal === value || (newVal !== newVal && value !== value)) {
        return
      }
      /* eslint-enable no-self-compare */
      if (process.env.NODE_ENV !== 'production' && customSetter) {
        customSetter()
      }
      if (setter) {
        setter.call(obj, newVal)
      } else {
        val = newVal
      }
      childOb = !shallow && observe(newVal)
      dep.notify()
    }
  })
}
复制代码

 let x = {}
 x['name'] = 'vue'
 console.log(Object.getOwnPropertyDescriptor(x,'name'))

Object.getOwnPropertyDescriptor可以获取对象某个key的描述对象，打印结果如下：
{
    value: "vue",
    writable: true,
    enumerable: true,
    configurable: true
}

Object.defineProperty(x, 'name', {
      configurable: false
})

let x = {}
x[1] = 2
x[2] = 4
Object.defineProperty(x, 2, {
     enumerable: false
})
for(let key in x){
    console.log("key:" + key + "|value:" +  x[key])
}

let dom = document.createElement('div');
for(let key in dom){
      console.log(key)
}

export default class VNode {
  tag: string | void;
  data: VNodeData | void;
  children: ?Array<VNode>;
  text: string | void;
  elm: Node | void;
  ns: string | void;
  context: Component | void; // rendered in this component's scope
  key: string | number | void;
  componentOptions: VNodeComponentOptions | void;
  componentInstance: Component | void; // component instance
  parent: VNode | void; // component placeholder node

  // strictly internal
  raw: boolean; // contains raw HTML? (server only)
  isStatic: boolean; // hoisted static node
  isRootInsert: boolean; // necessary for enter transition check
  isComment: boolean; // empty comment placeholder?
  isCloned: boolean; // is a cloned node?
  isOnce: boolean; // is a v-once node?
  asyncFactory: Function | void; // async component factory function
  asyncMeta: Object | void;
  isAsyncPlaceholder: boolean;
  ssrContext: Object | void;
  fnContext: Component | void; // real context vm for functional nodes
  fnOptions: ?ComponentOptions; // for SSR caching
  fnScopeId: ?string;
....
}

function getSum(a,b){
      return a+b;
}

function getSum(a){
      return function(b){
            return a+b;
      }
}

let f = getSum(2)
console.log(f(3))
console.log(getSum(2)(3)) //结果同上

console.log('script start');
setTimeout(function() {
    console.log('setTimeout');
    Promise.resolve().then(function() {
        console.log('promise3');
    }).then(function() {
        console.log('promise4');
    });
}, 0);
Promise.resolve().then(function() {
    console.log('promise1');
}).then(function() {
    console.log('promise2');
});
console.log('script end');
复制代码

script start
script end
promise1
promise2
setTimeout
promise3
promise4

    while (oldStartIdx <= oldEndIdx && newStartIdx <= newEndIdx) {
      if (isUndef(oldStartVnode)) {
        oldStartVnode = oldCh[++oldStartIdx]; // Vnode has been moved left
      } else if (isUndef(oldEndVnode)) {
        oldEndVnode = oldCh[--oldEndIdx];
      } else if (sameVnode(oldStartVnode, newStartVnode)) {
        patchVnode(oldStartVnode, newStartVnode, insertedVnodeQueue);
        oldStartVnode = oldCh[++oldStartIdx];
        newStartVnode = newCh[++newStartIdx];
      } else if (sameVnode(oldEndVnode, newEndVnode)) {
        patchVnode(oldEndVnode, newEndVnode, insertedVnodeQueue);
        oldEndVnode = oldCh[--oldEndIdx];
        newEndVnode = newCh[--newEndIdx];
      } else if (sameVnode(oldStartVnode, newEndVnode)) { // Vnode moved right
        patchVnode(oldStartVnode, newEndVnode, insertedVnodeQueue);
        canMove && nodeOps.insertBefore(parentElm, oldStartVnode.elm, nodeOps.nextSibling(oldEndVnode.elm));
        oldStartVnode = oldCh[++oldStartIdx];
        newEndVnode = newCh[--newEndIdx];
      } else if (sameVnode(oldEndVnode, newStartVnode)) { // Vnode moved left
        patchVnode(oldEndVnode, newStartVnode, insertedVnodeQueue);
        canMove && nodeOps.insertBefore(parentElm, oldEndVnode.elm, oldStartVnode.elm);
        oldEndVnode = oldCh[--oldEndIdx];
        newStartVnode = newCh[++newStartIdx];
      } else {
        if (isUndef(oldKeyToIdx)) { oldKeyToIdx = createKeyToOldIdx(oldCh, oldStartIdx, oldEndIdx); }
        idxInOld = isDef(newStartVnode.key)
          ? oldKeyToIdx[newStartVnode.key]
          : findIdxInOld(newStartVnode, oldCh, oldStartIdx, oldEndIdx);
        if (isUndef(idxInOld)) { // New element
          createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm, false, newCh, newStartIdx);
        } else {
          vnodeToMove = oldCh[idxInOld];
          if (sameVnode(vnodeToMove, newStartVnode)) {
            patchVnode(vnodeToMove, newStartVnode, insertedVnodeQueue);
            oldCh[idxInOld] = undefined;
            canMove && nodeOps.insertBefore(parentElm, vnodeToMove.elm, oldStartVnode.elm);
          } else {
            // same key but different element. treat as new element
            createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm, false, newCh, newStartIdx);
          }
        }
        newStartVnode = newCh[++newStartIdx];
      }

  const ast = parse(template.trim(), options)
  if (options.optimize !== false) {
    optimize(ast, options)
  }
  const code = generate(ast, options)
  return {
    ast,
    render: code.render,
    staticRenderFns: code.staticRenderFns
  }

   <li v-for="record in commits">
       <span class="date">{{record.commit.author.date}}</span>
   </li>

new Vue({
  // state
  data () {
    return {
      count: 0
    }
  },
  // view
  template: `
    <div>{{ count }}</div>
  `,
  // actions
  methods: {
    increment () {
      this.count++
    }
  }
})
复制代码

const store = new Vuex.Store({
  state: {
    token: 'xxx12345'
  },
  mutations: {
    changeToken(state, token) {
      state.token = token
    }
  }
})
// 通过mutation去改变token的状态值
store.commit('changeToken', 'xxxx12345555')

// 创建一个 tree 组件
const trees = {
  template: `<div>{{ tree }}</div>`,
  computed: {
    tree () {
      return store.state.tree
    }
  }
}
复制代码

const app = new Vue({
  el: '#app',
  // 把 store 对象提供给 “store” 选项，这可以把 store 的实例注入所有的子组件
  store,
  components: { trees },
  template: `
    <div class="app">
      <trees></trees>
    </div>
  `
})

const trees = {
  template: `<div>{{ tree }}</div>`,
  computed: {
    count () {
      return this.$store.state.tree
    }
  }
}
复制代码

computed: {
  doneTodosCount () {
    return this.$store.state.todos.filter(todo => todo.done).length
  }
}
复制代码

const store = new Vuex.Store({
  state: {
    todos: [
      { id: 1, text: '...', done: true },
      { id: 2, text: '...', done: false }
    ]
  },
  getters: {
    doneTodos: state => {
      return state.todos.filter(todo => todo.done)
    }
  }
})

store.getters.doneTodos // -> [{ id: 1, text: '...', done: true }]
Getter 也可以接受其他 getter 作为第二个参数：

getters: {
  // ...
  doneTodosCount: (state, getters) => {
    return getters.doneTodos.length
  }
}
store.getters.doneTodosCount // -> 1
我们可以很容易地在任何组件中使用它：

computed: {
  doneTodosCount () {
    return this.$store.getters.doneTodosCount
  }
}
复制代码

getters: {
  // ...
  getTodoById: (state) => (id) => {
    return state.todos.find(todo => todo.id === id)
  }
}
store.getters.getTodoById(2) // -> { id: 2, text: '...', done: false }

const store = new Vuex.Store({
  state: {
    count: 1
  },
  mutations: {
    increment (state) {
      state.count++
    }
  }
})

store.commit('increment')

mutations: {
  increment (state, n) {
    state.count += n
  }
}
store.commit('increment', 10)

mutations: {
  increment (state, payload) {
    state.count += payload.amount
  }
}
store.commit('increment', {
  amount: 10
})

store.commit({
  type: 'increment',
  amount: 10
})

mutations: {
  increment (state, payload) {
    state.count += payload.amount
  }
}

// mutation-types.js
export const SOME_MUTATION = 'SOME_MUTATION'
// store.js
import Vuex from 'vuex'
import { SOME_MUTATION } from './mutation-types'

const store = new Vuex.Store({
  state: { ... },
  mutations: {
    // 我们可以使用 ES2015 风格的计算属性命名功能来使用一个常量作为函数名
    [SOME_MUTATION] (state) {
      // mutate state
    }
  }
})

mutations: {
  someMutation (state) {
    api.callAsyncMethod(() => {
      state.count++
    })
  }
}

import { mapMutations } from 'vuex'

export default {
  // ...
  methods: {
    ...mapMutations([
      'increment', // 将 `this.increment()` 映射为 `this.$store.commit('increment')`

      // `mapMutations` 也支持载荷：
      'incrementBy' // 将 `this.incrementBy(amount)` 映射为 `this.$store.commit('incrementBy', amount)`
    ]),
    ...mapMutations({
      add: 'increment' // 将 `this.add()` 映射为 `this.$store.commit('increment')`
    })
  }
}

const store = new Vuex.Store({
  state: {
    count: 0
  },
  mutations: {
    increment (state) {
      state.count++
    }
  },
  actions: {
    increment (context) {
      context.commit('increment')
    }
  }
})

actions: {
  increment ({ commit }) {
    commit('increment')
  }
}

actions: {
  incrementAsync ({ commit }) {
    setTimeout(() => {
      commit('increment')
    }, 1000)
  }
}

// 以载荷形式分发
store.dispatch('incrementAsync', {
  amount: 10
})

// 以对象形式分发
store.dispatch({
  type: 'incrementAsync',
  amount: 10
})

actions: {
  checkout ({ commit, state }, products) {
    // 把当前购物车的物品备份起来
    const savedCartItems = [...state.cart.added]
    // 发出结账请求，然后乐观地清空购物车
    commit(types.CHECKOUT_REQUEST)
    // 购物 API 接受一个成功回调和一个失败回调
    shop.buyProducts(
      products,
      // 成功操作
      () => commit(types.CHECKOUT_SUCCESS),
      // 失败操作
      () => commit(types.CHECKOUT_FAILURE, savedCartItems)
    )
  }
}

import { mapActions } from 'vuex'

export default {
  // ...
  methods: {
    ...mapActions([
      'increment', // 将 `this.increment()` 映射为 `this.$store.dispatch('increment')`

      // `mapActions` 也支持载荷：
      'incrementBy' // 将 `this.incrementBy(amount)` 映射为 `this.$store.dispatch('incrementBy', amount)`
    ]),
    ...mapActions({
      add: 'increment' // 将 `this.add()` 映射为 `this.$store.dispatch('increment')`
    })
  }
}

actions: {
  actionA ({ commit }) {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        commit('someMutation')
        resolve()
      }, 1000)
    })
  }
}

store.dispatch('actionA').then(() => {
  // ...
})
在另外一个 action 中也可以：

actions: {
  // ...
  actionB ({ dispatch, commit }) {
    return dispatch('actionA').then(() => {
      commit('someOtherMutation')
    })
  }
}

actions: {
  async actionA ({ commit }) {
    commit('gotData', await getData())
  },
  async actionB ({ dispatch, commit }) {
    await dispatch('actionA') // 等待 actionA 完成
    commit('gotOtherData', await getOtherData())
  }
}

const moduleA = {
  state: { ... },
  mutations: { ... },
  actions: { ... },
  getters: { ... }
}

const moduleB = {
  state: { ... },
  mutations: { ... },
  actions: { ... }
}

const store = new Vuex.Store({
  modules: {
    a: moduleA,
    b: moduleB
  }
})

store.state.a // -> moduleA 的状态
store.state.b // -> moduleB 的状态

const moduleA = {
  state: { count: 0 },
  mutations: {
    increment (state) {
      // 这里的 `state` 对象是模块的局部状态
      state.count++
    }
  },

  getters: {
    doubleCount (state) {
      return state.count * 2
    }
  }
}

const moduleA = {
  // ...
  actions: {
    incrementIfOddOnRootSum ({ state, commit, rootState }) {
      if ((state.count + rootState.count) % 2 === 1) {
        commit('increment')
      }
    }
  }
}

const moduleA = {
  // ...
  getters: {
    sumWithRootCount (state, getters, rootState) {
      return state.count + rootState.count
    }
  }
}

const store = new Vuex.Store({
  modules: {
    account: {
      namespaced: true,

      // 模块内容（module assets）
      state: { ... }, // 模块内的状态已经是嵌套的了，使用 `namespaced` 属性不会对其产生影响
      getters: {
        isAdmin () { ... } // -> getters['account/isAdmin']
      },
      actions: {
        login () { ... } // -> dispatch('account/login')
      },
      mutations: {
        login () { ... } // -> commit('account/login')
      },

      // 嵌套模块
      modules: {
        // 继承父模块的命名空间
        myPage: {
          state: { ... },
          getters: {
            profile () { ... } // -> getters['account/profile']
          }
        },

        // 进一步嵌套命名空间
        posts: {
          namespaced: true,

          state: { ... },
          getters: {
            popular () { ... } // -> getters['account/posts/popular']
          }
        }
      }
    }
  }
})
复制代码

modules: {
  foo: {
    namespaced: true,

    getters: {
      // 在这个模块的 getter 中，`getters` 被局部化了
      // 你可以使用 getter 的第四个参数来调用 `rootGetters`
      someGetter (state, getters, rootState, rootGetters) {
        getters.someOtherGetter // -> 'foo/someOtherGetter'
        rootGetters.someOtherGetter // -> 'someOtherGetter'
      },
      someOtherGetter: state => { ... }
    },

    actions: {
      // 在这个模块中， dispatch 和 commit 也被局部化了
      // 他们可以接受 `root` 属性以访问根 dispatch 或 commit
      someAction ({ dispatch, commit, getters, rootGetters }) {
        getters.someGetter // -> 'foo/someGetter'
        rootGetters.someGetter // -> 'someGetter'

        dispatch('someOtherAction') // -> 'foo/someOtherAction'
        dispatch('someOtherAction', null, { root: true }) // -> 'someOtherAction'

        commit('someMutation') // -> 'foo/someMutation'
        commit('someMutation', null, { root: true }) // -> 'someMutation'
      },
      someOtherAction (ctx, payload) { ... }
    }
  }
}

{
  actions: {
    someOtherAction ({dispatch}) {
      dispatch('someAction')
    }
  },
  modules: {
    foo: {
      namespaced: true,

      actions: {
        someAction: {
          root: true,
          handler (namespacedContext, payload) { ... } // -> 'someAction'
        }
      }
    }
  }
}

computed: {
  ...mapState({
    a: state => state.some.nested.module.a,
    b: state => state.some.nested.module.b
  })
},
methods: {
  ...mapActions([
    'some/nested/module/foo', // -> this['some/nested/module/foo']()
    'some/nested/module/bar' // -> this['some/nested/module/bar']()
  ])
}

computed: {
  ...mapState('some/nested/module', {
    a: state => state.a,
    b: state => state.b
  })
},
methods: {
  ...mapActions('some/nested/module', [
    'foo', // -> this.foo()
    'bar' // -> this.bar()
  ])
}

import { createNamespacedHelpers } from 'vuex'

const { mapState, mapActions } = createNamespacedHelpers('some/nested/module')

export default {
  computed: {
    // 在 `some/nested/module` 中查找
    ...mapState({
      a: state => state.a,
      b: state => state.b
    })
  },
  methods: {
    // 在 `some/nested/module` 中查找
    ...mapActions([
      'foo',
      'bar'
    ])
  }
}

export function createPlugin (options = {}) {
  return function (store) {
    // 把空间名字添加到插件模块的类型（type）中去
    const namespace = options.namespace || ''
    store.dispatch(namespace + 'pluginAction')
  }
}

const MyReusableModule = {
  state () {
    return {
      foo: 'bar'
    }
  },
  // mutation, action 和 getter 等等...
}
复制代码

<template>
    <div>
        <h2>{{ msg }}</h2>
        <p>新闻ID：{{ $route.params.newsId}}</p>
        <p>新闻标题：{{ $route.params.newsTitle}}</p>
    </div>
</template>
<script>
export default {
  name: 'params',
  data () {
    return {
      msg: 'params page'
    }
  }
}
</script>
复制代码

   {
     path: '/query',
     name: 'Query',
     component: Query
   }

 <template>
  <div class="hello">
    <h1>{{ msg }}</h1>
    <router-view></router-view>
  </div>
</template>

 <template>
  <div class="hello">
    <h1>{{ msg }}</h1>
  </div>
</template>
<script>
  export default {
    data() {
      return {
        msg: 'I am H1 page,Welcome to H1'
      }
    }
  }
</script>
修改router/index.js代码，子路由的写法是在原有的路由配置下加入children字段。
   routes: [
    {
      path: '/',
      name: 'HelloWorld',
      component: HelloWorld,
      children: [{path: '/h1', name: 'H1', component: H1},//子路由的<router-view>必须在HelloWorld.vue中出现
        {path: '/h2', name: 'H2', component: H2}
      ]
    }
  ]
复制代码

<template>
  <div id="app">
    <img src="./assets/logo.png">
       <router-link :to="{name:'HelloWorld'}"><h1>H1</h1></router-link>
       <router-link :to="{name:'H1'}"><h1>H2</h1></router-link>
    <router-view></router-view>
    <router-view name="left" style="float:left;width:50%;background-color:#ccc;height:300px;"/>
    <router-view name="right" style="float:right;width:50%;background-color:yellowgreen;height:300px;"/>
  </div>
</template>

export default new Router({
    routes: [
      {
        path: '/',
        name: 'HelloWorld',
        components: {default: HelloWorld,
          left:H1,//显示H1组件内容'I am H1 page,Welcome to H1'
          right:H2//显示H2组件内容'I am H2 page,Welcome to H2'
        }
      },
      {
        path: '/h1',
        name: 'H1',
        components: {default: HelloWorld,
          left:H2,//显示H2组件内容
          right:H1//显示H1组件内容
        }
      }
    ]
  })

<script>
  export default{
    methods:{
      goToMenu(){
        this.$router.go(-1)//跳转到上一次浏览的页面
        this.$router.replace('/menu')//指定跳转的地址
        this.$router.replace({name:'menuLink'})//指定跳转路由的名字下
        this.$router.push('/menu')//通过push进行跳转
        this.$router.push({name:'menuLink'})//通过push进行跳转路由的名字下
      }
    }
  }
</script>
复制代码

<template>
    <div>
        <h2>{{ msg }}</h2>
    </div>
</template>
<script>
export default {
  data () {
    return {
      msg: 'Error:404'
    }
  }
}
</script>
复制代码

axios.get('/user?id=12345')
  .then(function (response) {
    console.log(response);
  })

axios.post('/user', {
    name: 'zxm'
  })
  .then(function (response) {
    console.log(response);
  })

'use strict';

var utils = require('./utils');
var bind = require('./helpers/bind');
var Axios = require('./core/Axios');
var mergeConfig = require('./core/mergeConfig');
var defaults = require('./defaults');

// 重点 createInstance 方法
// 先眼熟一个代码 下面讲完工具函数会再具体来讲解 createInstance
function createInstance(defaultConfig) {
    // 实例化 Axios
  var context = new Axios(defaultConfig);
    // 自定义 bind 方法 返回一个函数（）=> {Axios.prototype.request.apply(context,args)}
  var instance = bind(Axios.prototype.request, context);
    // Axios 源码的工具类
  utils.extend(instance, Axios.prototype, context);

  utils.extend(instance, context);

  return instance;
}
// 传入一个默认配置   defaults 配置先不管，后面会有具体的细节
var axios = createInstance(defaults);


// 下面都是为 axios 实例化的对象增加不同的方法。
axios.Axios = Axios;
axios.create = function create(instanceConfig) {
  return createInstance(mergeConfig(axios.defaults, instanceConfig));
};
axios.Cancel = require('./cancel/Cancel');
axios.CancelToken = require('./cancel/CancelToken');
axios.isCancel = require('./cancel/isCancel');
axios.all = function all(promises) {
  return Promise.all(promises);
};
axios.spread = require('./helpers/spread');
module.exports = axios;
module.exports.default = axios;

module.exports = {
  isArray: isArray,
  isArrayBuffer: isArrayBuffer,
  isBuffer: isBuffer,
  isFormData: isFormData,
  isArrayBufferView: isArrayBufferView,
  isString: isString,
  isNumber: isNumber,
  isObject: isObject,
  isUndefined: isUndefined,
  isDate: isDate,
  isFile: isFile,
  isBlob: isBlob,
  isFunction: isFunction,
  isStream: isStream,
  isURLSearchParams: isURLSearchParams,
  isStandardBrowserEnv: isStandardBrowserEnv,
  forEach: forEach,
  merge: merge,
  deepMerge: deepMerge,
  extend: extend,
  trim: trim
};

// a, b，thisArg 参数都为一个对象
function extend(a, b, thisArg) {
  forEach(b, function assignValue(val, key) {
      // 如果指定了 thisArg 那么绑定执行上下文到 thisArg
    if (thisArg && typeof val === 'function') {
      a[key] = bind(val, thisArg);
    } else {
      a[key] = val;
    }
  });
  return a;
}

'use strict';
var utils = require('./../utils');
var buildURL = require('../helpers/buildURL');
var InterceptorManager = require('./InterceptorManager');
var dispatchRequest = require('./dispatchRequest');
var mergeConfig = require('./mergeConfig');

function Axios(instanceConfig) {
  this.defaults = instanceConfig;
  this.interceptors = {
    request: new InterceptorManager(),
    response: new InterceptorManager()
  };
}

// 核心方法 request
Axios.prototype.request = function request(config) {
  // ... 单独讲
};

// 合并配置将用户的配置 和默认的配置合并
Axios.prototype.getUri = function getUri(config) {
  config = mergeConfig(this.defaults, config);
  return buildURL(config.url, config.params, config.paramsSerializer).replace(/^\?/, '');
};
// 这个就是给 Axios.prototype 上面增加 delete,get,head,options 方法
// 这样我们就可以使用 axios.get(), axios.post() 等等方法
utils.forEach(['delete', 'get', 'head', 'options'], function forEachMethodNoData(method) {
  Axios.prototype[method] = function(url, config) {
     // 都是调用了 this.request 方法
    return this.request(utils.merge(config || {}, {
      method: method,
      url: url
    }));
  };
});
utils.forEach(['post', 'put', 'patch'], function forEachMethodWithData(method) {
  Axios.prototype[method] = function(url, data, config) {
    return this.request(utils.merge(config || {}, {
      method: method,
      url: url,
      data: data
    }));
  };
});

module.exports = Axios;

function Axios(instanceConfig) {
  this.defaults = instanceConfig;
  this.interceptors = {
    request: new InterceptorManager(),
    response: new InterceptorManager()
  };
}
Axios.prototype.request = function request(config) {
  // Allow for axios('example/url'[, config]) a la fetch API
  if (typeof config === 'string') {
    config = arguments[1] || {};
    config.url = arguments[0];
  } else {
    config = config || {};
  }
    // 合并配置
  config = mergeConfig(this.defaults, config);
    // 请求方式，没有默认为 get
  config.method = config.method ? config.method.toLowerCase() : 'get';

    // 重点 这个就是拦截器的中间件
  var chain = [dispatchRequest, undefined];
    // 生成一个 promise 对象
  var promise = Promise.resolve(config);

    // 将请求前方法置入 chain 数组的前面 一次置入两个 成功的，失败的
  this.interceptors.request.forEach(function unshiftRequestInterceptors(interceptor) {
    chain.unshift(interceptor.fulfilled, interceptor.rejected);
  });
	// 将请求后的方法置入 chain 数组的后面 一次置入两个 成功的，失败的
  this.interceptors.response.forEach(function pushResponseInterceptors(interceptor) {
    chain.push(interceptor.fulfilled, interceptor.rejected);
  });

   // 通过 shift 方法把第一个元素从其中删除，并返回第一个元素。
  while (chain.length) {
    promise = promise.then(chain.shift(), chain.shift());
  }

  return promise;
};

'use strict';
var utils = require('./../utils');

function InterceptorManager() {
    // 存放方法的数组
  this.handlers = [];
}
// 通过 use 方法来添加拦截方法
InterceptorManager.prototype.use = function use(fulfilled, rejected) {
  this.handlers.push({
    fulfilled: fulfilled,
    rejected: rejected
  });
  return this.handlers.length - 1;
};
// 通过 eject 方法来删除拦截方法
InterceptorManager.prototype.eject = function eject(id) {
  if (this.handlers[id]) {
    this.handlers[id] = null;
  }
};
// 添加一个 forEach 方法，这就是上述说的 forEach
InterceptorManager.prototype.forEach = function forEach(fn) {
    // 里面还是依旧使用了 utils 的 forEach， 不要纠结这些 forEach 的具体代码
    // 明白他们干了什么就可以
  utils.forEach(this.handlers, function forEachHandler(h) {
    if (h !== null) {
      fn(h);
    }
  });
};

module.exports = InterceptorManager;


复制代码

'use strict';
var utils = require('./../utils');
var transformData = require('./transformData');
var isCancel = require('../cancel/isCancel');
var defaults = require('../defaults');
var isAbsoluteURL = require('./../helpers/isAbsoluteURL');
var combineURLs = require('./../helpers/combineURLs');
// 请求取消时候的方法，暂不看
function throwIfCancellationRequested(config) {
  if (config.cancelToken) {
    config.cancelToken.throwIfRequested();
  }
}

module.exports = function dispatchRequest(config) {
  throwIfCancellationRequested(config);
    // 请求没有取消 执行下面的请求
  if (config.baseURL && !isAbsoluteURL(config.url)) {
    config.url = combineURLs(config.baseURL, config.url);
  }
  config.headers = config.headers || {};
	// 转换数据
  config.data = transformData(
    config.data,
    config.headers,
    config.transformRequest
  );
    // 合并配置
  config.headers = utils.merge(
    config.headers.common || {},
    config.headers[config.method] || {},
    config.headers || {}
  );
  utils.forEach(
    ['delete', 'get', 'head', 'post', 'put', 'patch', 'common'],
    function cleanHeaderConfig(method) {
      delete config.headers[method];
    }
  );
    // 这里是重点， 获取请求的方式，下面会将到
  var adapter = config.adapter || defaults.adapter;
  return adapter(config).then(function onAdapterResolution(response) {
    throwIfCancellationRequested(config);
	// 难道了请求的数据， 转换 data
    response.data = transformData(
      response.data,
      response.headers,
      config.transformResponse
    );
    return response;
  }, function onAdapterRejection(reason) {
      // 失败处理
    if (!isCancel(reason)) {
      throwIfCancellationRequested(config);

      // Transform response data
      if (reason && reason.response) {
        reason.response.data = transformData(
          reason.response.data,
          reason.response.headers,
          config.transformResponse
        );
      }
    }

    return Promise.reject(reason);
  });
};

'use strict';

var utils = require('./utils');
var normalizeHeaderName = require('./helpers/normalizeHeaderName');

var DEFAULT_CONTENT_TYPE = {
  'Content-Type': 'application/x-www-form-urlencoded'
};

function setContentTypeIfUnset(headers, value) {
  if (!utils.isUndefined(headers) && utils.isUndefined(headers['Content-Type'])) {
    headers['Content-Type'] = value;
  }
}
// getDefaultAdapter 方法是来获取请求的方式
function getDefaultAdapter() {
  var adapter;
  // process 是 node 环境的全局变量
  if (typeof process !== 'undefined' && Object.prototype.toString.call(process) === '[object process]') {
    // 如果是 node 环境那么久通过 node http 的请求方法
    adapter = require('./adapters/http');
  } else if (typeof XMLHttpRequest !== 'undefined') {
   // 如果是浏览器啥的 有 XMLHttpRequest 的就用 XMLHttpRequest
    adapter = require('./adapters/xhr');
  }
  return adapter;
}

var defaults = {
    // adapter 就是请求的方法
  adapter: getDefaultAdapter(),
	// 下面一些请求头，转换数据，请求,详情的数据
    // 这也就是为什么我们可以直接拿到请求的数据时一个对象，如果用 ajax 我们拿到的都是 jSON 格式的字符串
    // 然后每次都通过 JSON.stringify（data）来处理结果。
  transformRequest: [function transformRequest(data, headers) {
    normalizeHeaderName(headers, 'Accept');
    normalizeHeaderName(headers, 'Content-Type');
    if (utils.isFormData(data) ||
      utils.isArrayBuffer(data) ||
      utils.isBuffer(data) ||
      utils.isStream(data) ||
      utils.isFile(data) ||
      utils.isBlob(data)
    ) {
      return data;
    }
    if (utils.isArrayBufferView(data)) {
      return data.buffer;
    }
    if (utils.isURLSearchParams(data)) {
      setContentTypeIfUnset(headers, 'application/x-www-form-urlencoded;charset=utf-8');
      return data.toString();
    }
    if (utils.isObject(data)) {
      setContentTypeIfUnset(headers, 'application/json;charset=utf-8');
      return JSON.stringify(data);
    }
    return data;
  }],

  transformResponse: [function transformResponse(data) {
    /*eslint no-param-reassign:0*/
    if (typeof data === 'string') {
      try {
        data = JSON.parse(data);
      } catch (e) { /* Ignore */ }
    }
    return data;
  }],

  /**
   * A timeout in milliseconds to abort a request. If set to 0 (default) a
   * timeout is not created.
   */
  timeout: 0,

  xsrfCookieName: 'XSRF-TOKEN',
  xsrfHeaderName: 'X-XSRF-TOKEN',

  maxContentLength: -1,

  validateStatus: function validateStatus(status) {
    return status >= 200 && status < 300;
  }
};

defaults.headers = {
  common: {
    'Accept': 'application/json, text/plain, */*'
  }
};

utils.forEach(['delete', 'get', 'head'], function forEachMethodNoData(method) {
  defaults.headers[method] = {};
});

utils.forEach(['post', 'put', 'patch'], function forEachMethodWithData(method) {
  defaults.headers[method] = utils.merge(DEFAULT_CONTENT_TYPE);
});

module.exports = defaults;


复制代码