用150行程式碼實現Vuex 80%的功能

Vuex · 發表 2019-02-12 23:50:11

摘要：作者：殷榮檜@騰訊本文地址 ,歡迎檢視本文 github倉庫程式碼地址，歡迎star，謝謝。如果你對自己用少量程式碼實現各個框架感興趣，那下面這些你都可以一看： build-your-own-react build-your-own-flux ...

作者：殷榮檜@騰訊

本文地址 ,歡迎檢視

本文 github倉庫程式碼地址，歡迎star，謝謝。

如果你對自己用少量程式碼實現各個框架感興趣，那下面這些你都可以一看：

build-your-own-react

build-your-own-flux

build-your-own-redux

export class Store {
constructor(options = {}, Vue) {
this.options = options;
Vue.mixin({ beforeCreate: vuexInit });
}
get state () {
return this.options.state;
}
}
function vuexInit () {
const options = this.$options
if (options.store) {
// 元件內部設定了store,則優先使用元件內部的store
this.$store = typeof options.store === 'function'
? options.store()
: options.store
} else if (options.parent && options.parent.$store) {
// 元件內部沒有設定store,則從根App.vue下繼承$store方法
this.$store = options.parent.$store
}
}
複製程式碼

介面程式碼如下：

<script>
export default {
name: 'app',
created() {
console.log('打印出this.$store.state.count的結果',this.$store.state.count);
},
}
</script>
複製程式碼

執行結果: 成功打印出this.$store.state.count的值為0

二. vuex中的getter方法的實現

main.js程式碼如下：

let store = new Vuex.Store({
state: {
count: 0
},
getters: {
getStatePlusOne(state) {
return state.count + 1
}
}

}, Vue);

new Vue({
store,
render: h => h(App),
}).$mount('#app')
複製程式碼

store.js的程式碼如下：

export class Store {
constructor(options = {}, Vue) {
this.options = options;
this.getters = {}
Vue.mixin({ beforeCreate: vuexInit });
forEachValue(options.getters, (getterFn, getterName) => {
registerGetter(this, getterName, getterFn);
})
}
get state() {
return this.options.state;
}
}

function registerGetter(store, getterName, getterFn) {
Object.defineProperty(store.getters, getterName, {
get: () => {
return getterFn(store.state)
}
})
}

// 將物件中的每一個值放入到傳入的函式中作為引數執行
function forEachValue(obj, fn) {
Object.keys(obj).forEach(key => fn(obj[key], key));
}

function vuexInit() {
const options = this.$options
if (options.store) {
// 元件內部設定了store,則優先使用元件內部的store
this.$store = typeof options.store === 'function' ?
options.store() :
options.store
} else if (options.parent && options.parent.$store) {
// 元件內部沒有設定store,則從根App.vue下繼承$store方法
this.$store = options.parent.$store
}
}
複製程式碼

介面程式碼如下：

<script>
export default {
name: 'app',
created() {
console.log('打印出this.$store.getters.getStatePlusOne的結果',this.$store.getters.getStatePlusOne);
},
}
</script>
複製程式碼

執行結果：成功打印出this.$store.getters.getStatePlusOne的值為1

三. mutation和commit方法的實現

main.js程式碼如下：

let store = new Vuex.Store({
state: {
count: 0
},
mutations: {
incrementFive(state) {
// console.log('初始state', JSON.stringify(state));
state.count = state.count + 5;
}
},
getters: {
getStatePlusOne(state) {
return state.count + 1
}
}

}, Vue);
複製程式碼

store.js的程式碼如下：

export class Store {
constructor(options = {}, Vue) {
Vue.mixin({ beforeCreate: vuexInit })
this.options = options;
this.getters = {};
this.mutations = {};
const { commit } = this;
this.commit = (type) => {
return commit.call(this, type);
}
forEachValue(options.getters, (getterFn, getterName) => {
registerGetter(this, getterName, getterFn);
});

forEachValue(options.mutations, (mutationFn, mutationName) => {
registerMutation(this, mutationName, mutationFn)
});

this._vm = new Vue({
data: {
state: options.state
}
});
}

get state() {
// return this.options.state; // 無法完成頁面中的雙向繫結，所以改用this._vm的形式
return this._vm._data.state;
}
commit(type) {
this.mutations[type]();
}
}

function registerMutation(store, mutationName, mutationFn) {
store.mutations[mutationName] = () => {
mutationFn.call(store, store.state);
}
}


function registerGetter(store, getterName, getterFn) {
Object.defineProperty(store.getters, getterName, {
get: () => {
return getterFn(store.state)
}
})
}

// 將物件中的每一個值放入到傳入的函式中作為引數執行
function forEachValue(obj, fn) {
Object.keys(obj).forEach(key => fn(obj[key], key));
}

function vuexInit() {
const options = this.$options
if (options.store) {
// 元件內部設定了store,則優先使用元件內部的store
this.$store = typeof options.store === 'function' ?
options.store() :
options.store
} else if (options.parent && options.parent.$store) {
// 元件內部沒有設定store,則從根App.vue下繼承$store方法
this.$store = options.parent.$store
}
}
複製程式碼

介面程式碼如下：

<script>
export default {
name: 'app',
created() {
console.log('打印出this.$store.getters.getStatePlusOne的結果',this.$store.getters.getStatePlusOne);
},
mounted() {
setTimeout(() => {
this.$store.commit('incrementFive');
console.log('store state自增5後的結果', this.$store.state.count);
}, 2000);
},
computed: {
count() {
return this.$store.state.count;
}
}
}
</script>
複製程式碼

執行結果：成功在2秒之後輸出count自增5後的結果5

四. actions和dispatch方法的實現

main.js程式碼如下：

let store = new Vuex.Store({
state: {
count: 0
},
actions: {
countPlusSix(context) {
context.commit('plusSix');
}
},
mutations: {
incrementFive(state) {
// console.log('初始state', JSON.stringify(state));
state.count = state.count + 5;
},
plusSix(state) {
state.count = state.count + 6;
}
},
getters: {
getStatePlusOne(state) {
return state.count + 1
}
}

}, Vue);
複製程式碼

store.js的程式碼如下：

export class Store {
constructor(options = {}, Vue) {
Vue.mixin({ beforeCreate: vuexInit })
this.options = options;
this.getters = {};
this.mutations = {};
this.actions = {};
const { dispatch, commit } = this;
this.commit = (type) => {
return commit.call(this, type);
}
this.dispatch = (type) => {
return dispatch.call(this, type);
}
forEachValue(options.actions, (actionFn, actionName) => {
registerAction(this, actionName, actionFn);
});

forEachValue(options.getters, (getterFn, getterName) => {
registerGetter(this, getterName, getterFn);
});

forEachValue(options.mutations, (mutationFn, mutationName) => {
registerMutation(this, mutationName, mutationFn)
});

this._vm = new Vue({
data: {
state: options.state
}
});
}

get state() {
// return this.options.state; // 無法完成頁面中的雙向繫結，所以改用this._vm的形式
return this._vm._data.state;
}
commit(type) {
this.mutations[type]();
}
dispatch(type) {
return this.actions[type]();
}
}

function registerMutation(store, mutationName, mutationFn) {
store.mutations[mutationName] = () => {
mutationFn.call(store, store.state);
}
}

function registerAction(store, actionName, actionFn) {
store.actions[actionName] = () => {
actionFn.call(store, store)
}
}

function registerGetter(store, getterName, getterFn) {
Object.defineProperty(store.getters, getterName, {
get: () => {
return getterFn(store.state)
}
})
}

// 將物件中的每一個值放入到傳入的函式中作為引數執行
function forEachValue(obj, fn) {
Object.keys(obj).forEach(key => fn(obj[key], key));
}

function vuexInit() {
const options = this.$options
if (options.store) {
// 元件內部設定了store,則優先使用元件內部的store
this.$store = typeof options.store === 'function' ?
options.store() :
options.store
} else if (options.parent && options.parent.$store) {
// 元件內部沒有設定store,則從根App.vue下繼承$store方法
this.$store = options.parent.$store
}
}
複製程式碼

介面程式碼如下：

export default {
name: 'app',
created() {
console.log('打印出this.$store.getters.getStatePlusOne的結果',this.$store.getters.getStatePlusOne);
},
mounted() {
setTimeout(() => {
this.$store.commit('incrementFive');
console.log('store state自增5後的結果', this.$store.state.count);
}, 2000);
setTimeout(() => {
this.$store.dispatch('countPlusSix');
console.log('store dispatch自增6後的結果', this.$store.state.count);
}, 3000);
},
computed: {
count() {
return this.$store.state.count;
}
}
}
複製程式碼

執行結果：成功在3秒之後dipatch自增6輸出11

五. module方法的實現

main.js程式碼如下：

const pageA = {
state: {
count: 100
},
mutations: {
incrementA(state) {
state.count++;
}
},
actions: {
incrementAAction(context) {
context.commit('incrementA');
}
}
}

let store = new Vuex.Store({
modules: {
a: pageA
},
state: {
count: 0
},
actions: {
countPlusSix(context) {
context.commit('plusSix');
}
},
mutations: {
incrementFive(state) {
// console.log('初始state', JSON.stringify(state));
state.count = state.count + 5;
},
plusSix(state) {
state.count = state.count + 6;
}
},
getters: {
getStatePlusOne(state) {
return state.count + 1
}
}

}, Vue);
複製程式碼

store.js的程式碼如下：

let _Vue;
export class Store {
constructor(options = {}, Vue) {
_Vue = Vue
Vue.mixin({ beforeCreate: vuexInit })
this.getters = {};
this._mutations = {}; // 在私有屬性前加_
this._wrappedGetters = {};
this._actions = {};
this._modules = new ModuleCollection(options)
const { dispatch, commit } = this;
this.commit = (type) => {
return commit.call(this, type);
}
this.dispatch = (type) => {
return dispatch.call(this, type);
}
const state = options.state;
const path = []; // 初始路徑給根路徑為空
installModule(this, state, path, this._modules.root);
this._vm = new Vue({
data: {
state: state
}
});
}

get state() {
// return this.options.state; // 無法完成頁面中的雙向繫結，所以改用this._vm的形式
return this._vm._data.state;
}
commit(type) {
this._mutations[type].forEach(handler => handler());
}
dispatch(type) {
return this._actions[type][0]();
}
}

class ModuleCollection {
constructor(rawRootModule) {
this.register([], rawRootModule)
}
register(path, rawModule) {
const newModule = {
_children: {},
_rawModule: rawModule,
state: rawModule.state
}
if (path.length === 0) {
this.root = newModule;
} else {
const parent = path.slice(0, -1).reduce((module, key) => {
return module._children(key);
}, this.root);
parent._children[path[path.length - 1]] = newModule;
}
if (rawModule.modules) {
forEachValue(rawModule.modules, (rawChildModule, key) => {
this.register(path.concat(key), rawChildModule);
})
}
}
}

function installModule(store, rootState, path, module) {
if (path.length > 0) {
const parentState = rootState;
const moduleName = path[path.length - 1];
_Vue.set(parentState, moduleName, module.state)
}
const context = {
dispatch: store.dispatch,
commit: store.commit,
}
const local = Object.defineProperties(context, {
getters: {
get: () => store.getters
},
state: {
get: () => {
let state = store.state;
return path.length ? path.reduce((state, key) => state[key], state) : state
}
}
})
if (module._rawModule.actions) {
forEachValue(module._rawModule.actions, (actionFn, actionName) => {
registerAction(store, actionName, actionFn, local);
});
}
if (module._rawModule.getters) {
forEachValue(module._rawModule.getters, (getterFn, getterName) => {
registerGetter(store, getterName, getterFn, local);
});
}
if (module._rawModule.mutations) {
forEachValue(module._rawModule.mutations, (mutationFn, mutationName) => {
registerMutation(store, mutationName, mutationFn, local)
});
}
forEachValue(module._children, (child, key) => {
installModule(store, rootState, path.concat(key), child)
})

}

function registerMutation(store, mutationName, mutationFn, local) {
const entry = store._mutations[mutationName] || (store._mutations[mutationName] = []);
entry.push(() => {
mutationFn.call(store, local.state);
});
}

function registerAction(store, actionName, actionFn, local) {
const entry = store._actions[actionName] || (store._actions[actionName] = [])
entry.push(() => {
return actionFn.call(store, {
commit: local.commit,
state: local.state,
})
});
}

function registerGetter(store, getterName, getterFn, local) {
Object.defineProperty(store.getters, getterName, {
get: () => {
return getterFn(
local.state,
local.getters,
store.state
)
}
})
}

// 將物件中的每一個值放入到傳入的函式中作為引數執行
function forEachValue(obj, fn) {
Object.keys(obj).forEach(key => fn(obj[key], key));
}

function vuexInit() {
const options = this.$options
if (options.store) {
// 元件內部設定了store,則優先使用元件內部的store
this.$store = typeof options.store === 'function' ?
options.store() :
options.store
} else if (options.parent && options.parent.$store) {
// 元件內部沒有設定store,則從根App.vue下繼承$store方法
this.$store = options.parent.$store
}
}
複製程式碼

主介面程式碼如下：

<template>
<div id="app">
==============主頁================<br>
主頁數量count為: {{count}}<br>
pageA數量count為: {{countA}}<br>
==========以下為PageA內容==========<br>
<page-a></page-a>
</div>
</template>

<script>
import pageA from './pageA';

export default {
name: 'app',
components: {
pageA
},
created() {
console.log('打印出this.$store.getters.getStatePlusOne的結果',this.$store.getters.getStatePlusOne);
},
mounted() {
setTimeout(() => {
this.$store.commit('incrementFive');
console.log('store state自增5後的結果', this.$store.state.count);
}, 2000);
setTimeout(() => {
this.$store.dispatch('countPlusSix');
console.log('store dispatch自增6後的結果', this.$store.state.count);
}, 3000);
},
computed: {
count() {
return this.$store.state.count;
},
countA() {
return this.$store.state.a.count;
}
}
}
</script>
複製程式碼

pageA頁面如下：

<template>
<div>
頁面A被載入
</div>
</template>

<script>
export default {
name: 'pageA',
mounted() {
setTimeout(() => {
this.$store.dispatch('incrementAAction');
}, 5000)
},
}
</script>
複製程式碼

執行結果：在5秒後A頁面觸發incrementAAction，主介面中的countA變化為101，成功

自此：基本用了150行左右的程式碼實現了vuex 80%左右的功能了，其中還有namespace等不能夠使用，其他基本都和原始碼語法相同，如果你有興趣仔細再看看，可以移步 github倉庫程式碼，程式碼是建立在閱讀了vuex原始碼之後寫的，所以看完了本文的程式碼，再去看vuex的程式碼，相信你一定會一目瞭然

六. 實現：Vue.use(Vuex)

最後為了和vuex原始碼做到最相似，同樣使用Vue.use(Vuex),使用如下的程式碼進行實現：

export function install(_Vue) {
Vue = _Vue;
Vue.mixin({
beforeCreate: function vuexInit() {
const options = this.$options;
if (options.store) {
this.$store = options.store;
} else if (options.parent && options.parent.$store) {
this.$store = options.parent.$store;
}
}
})
}
複製程式碼

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參考資料：

Build a Vuex Module

How does a minimal Vuex implementation look like?

從0開始寫一個自己的Vuex

vuex 原始碼：如何實現一個簡單的 vuex