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简单文章
首先,我们来看package.json文件
"scripts": {
"serve": "vue-cli-service serve",
"build": "vue-cli-service build"
}
看到,这里明显是使用了vue-cli-service指令来打包;那我们看看vue-cli-service,是如何进行打包的;
众所周知,vue-cli-service是vue-cli的一个插件;vue-cli-service serve 命令主要用于在开发阶段构建项目,包括热加载这一套,下面开始简单分析下整个代码。通过前面对 @vue/cli-service 的整体分析, 可以发现,vue-cli-service 所有的 CLI 命令服务都是动态注册的,包括环境变量文件加载,获取项目配置信息,合并项目配置,加载插件等等,最后执行对应 CLI 命令服务:
async run (name, args = {}, rawArgv = []) {
...
const { fn } = command
return fn(args, rawArgv)
}
而这个command指令,就是通过 api.registerCommand 来注册命令的:
module.exports = (api, options) => {
api.registerCommand('serve', {
// ...
}, async function serve (args) {
// 代码较多
})
}
这里就简单找到了,uni-cli是如何做到全局指令的;而后面就大概梳理一下vue-cli,vue-cli-service和vue-cli-plugin-uni以及其他配置产生的关系:
如上图,我们的uni-cli同样是通过webpack配置来进行项目打包配置的;具体的配置通过了vue-cli-plugin-uni的初始配置./lib/config-wepback.js
和./lib/chain-webpack.js
以及./lib/"platform"
的配置;然后再经过vue-cli-service,加入了开发环境的配置,如hot-reload middleware;同时会使用项目中的vue.config.js内的配置去覆盖原本配置。
so,总结结论,配置权重: vue.config.js > vue-cli-service > vue-cli-plugin-uni;但是vue-cli-plugin-uni也会被pages.json和manifest.json影响;
mpvue源码
Vue$3.prototype._initMP = initMP;
Vue$3.prototype.$updateDataToMP = updateDataToMP;
Vue$3.prototype._initDataToMP = initDataToMP;
Vue$3.prototype.$handleProxyWithVue = handleProxyWithVue;
return Vue$3;
整体文件都在为了这个Vue$3构建函数;这个构建函数,请大致看一下Vue.prototype._init部分;
Vue.prototype._init = function (options) {
...
initLifecycle(vm);
initEvents(vm);
initRender(vm);
callHook(vm, 'beforeCreate');
initInjections(vm); // resolve injections before data/props
initState(vm);
initProvide(vm); // resolve provide after data/props
callHook(vm, 'created');
}
上面就是mpvue的类似constrator的构建函数;
众所周知,小程序app由Page和Component组成,那是如何和vue进行的绑定呢?
Vue$3.prototype.$mount = function (el, hydrating) {
var this$1 = this;
// 初始化小程序生命周期相关
var options = this.$options;
if (options && (options.render || options.mpType)) {
var mpType = options.mpType; if ( mpType === void 0 ) mpType = 'page';
return this._initMP(mpType, function () {
return mountComponent(this$1, undefined, undefined)
})
} else {
return mountComponent(this, undefined, undefined)
}
};
function initMP (mpType, next) {
...
if (mp.status) {
// 处理子组件的小程序生命周期
if (mpType === 'app') {
callHook$1(this, 'onLaunch', mp.appOptions);
} else {
callHook$1(this, 'onLoad', mp.query);
callHook$1(this, 'onReady');
}
return next()
}
// mp.registered = true
mp.mpType = mpType;
mp.status = 'register';
if (mpType === 'app') {
global.App({
// 页面的初始数据
globalData: {
appOptions: {}
},
handleProxy: function handleProxy (e) {
...
},
// Do something initial when launch.
onLaunch: function onLaunch (options) {
...
},
// Do something when app show.
onShow: function onShow (options) {
...
},
// Do something when app hide.
onHide: function onHide () {
...
},
});
} else if (mpType === 'component') {
initMpProps(rootVueVM);
global.Component({
// 小程序原生的组件属性
...
});
} else {
var app = global.getApp();
global.Page({
// 页面的初始数据
...
});
}
}
这里可见,initMP的时候,就会被打上对应的标记mpType,而且不同的mpType会初始化不一样的,分别对应小程序的App,Page和自定义组件Component;并且通过callHook$1来触发mpvue定义的回调(这些生命周期的钩子就是vue的钩子);这就完美地将vue的生命周期和小程序生命周期进行了关联;
还是看到最底下的Vue$3构建函数:
Vue$3.prototype._initMP = initMP;
Vue$3.prototype.$updateDataToMP = updateDataToMP;
Vue$3.prototype._initDataToMP = initDataToMP;
Vue$3.prototype.$handleProxyWithVue = handleProxyWithVue;
其中,观察initDataToMP和updateDataToMP:
function initDataToMP () {
var page = getPage(this);
if (!page) {
return
}
var data = collectVmData(this.$root);
page.setData(data);
}
initDataToMP调用了collectVmData,递归得到当前组件和及其子组件下的所有数据(包括props,data,computed,watch)。
这里大家可以看看实际得到的一个数据:
然后再通过节流函数以及setData
做数据更新;
ok,至此,mpvue的数据转化成小程序的数据,已经清晰了;但是,mpvue是如何做到跟踪数据的变化呢?
还是利用了发布订阅模式;
发布订阅模式比较常见,这里仅介绍一下了;具体的函数,可以见initState;这里只看ovserve:
function observe (value, asRootData, key) {
if (!isObject(value)) {
return
}
var ob;
if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
ob = value.__ob__;
} else if (
observerState.shouldConvert &&
!isServerRendering() &&
(Array.isArray(value) || isPlainObject(value)) &&
Object.isExtensible(value) &&
!value._isVue
) {
ob = new Observer(value, key);
}
if (asRootData && ob) {
ob.vmCount++;
}
return ob
}
里面Observer的观察者:
var Observer = function Observer (value, key) {
this.value = value;
this.dep = new Dep();
this.vmCount = 0;
if (key) {
this.key = key;
}
def(value, '__ob__', this);
if (Array.isArray(value)) {
var augment = hasProto
? protoAugment
: copyAugment;
augment(value, arrayMethods, arrayKeys);
this.observeArray(value);
} else {
this.walk(value);
}
};
其中,关键核心在于augment(value, arrayMethods, arrayKeys);
和this.observeArray(value);
;将数据全部推送给观察者;
function defineReactive$$1 (
obj,
key,
val,
customSetter,
shallow
) {
var dep = new Dep();
var property = Object.getOwnPropertyDescriptor(obj, key);
if (property && property.configurable === false) {
return
}
// cater for pre-defined getter/setters
var getter = property && property.get;
var setter = property && property.set;
var childOb = !shallow && observe(val, undefined, key);
Object.defineProperty(obj, key, {
enumerable: true,
configurable: true,
get: function reactiveGetter () {
var 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) {
var 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 ("production" !== 'production' && customSetter) {
customSetter();
}
if (setter) {
setter.call(obj, newVal);
} else {
val = newVal;
}
childOb = !shallow && observe(newVal, undefined, key);
dep.notify();
if (!obj.__keyPath) {
def(obj, '__keyPath', {}, false);
}
obj.__keyPath[key] = true;
if (newVal instanceof Object && !(newVal instanceof Array)) {
// 标记是否是通过this.Obj = {} 赋值印发的改动,解决少更新问题#1305
def(newVal, '__newReference', true, false);
}
}
});
}
上面是使用典型的getter和setter的劫持
在挂载组件的时候,Vue$3.prototype.$mount的时候,就创建了一个watcher的观察器;
vm._watcher = new Watcher(vm, updateComponent, noop);
....
this.value = this.lazy
? undefined
: this.get();
watcher观察器中的get方法:
Watcher.prototype.get = function get () {
pushTarget(this);
var value;
var vm = this.vm;
try {
value = this.getter.call(vm, vm);
} catch (e) {
if (this.user) {
handleError(e, vm, ("getter for watcher \"" + (this.expression) + "\""));
} else {
throw e
}
} finally {
// "touch" every property so they are all tracked as
// dependencies for deep watching
if (this.deep) {
traverse(value);
}
popTarget();
this.cleanupDeps();
}
return value
};
其中,Dep是一个观察者数组,可以通过addSub
,removeSub
增加和删减需要观察的字段,另外提供notify
进行发布的通知;
Dep.prototype.notify = function notify () {
// stabilize the subscriber list first
var subs = this.subs.slice();
for (var i = 0, l = subs.length; i < l; i++) {
subs[i].update();
}
};
所以,当set方法调用的时候,会调用notify,来通知Dep实例上加入的订阅者watcher,最后调用watcher的update方法;
Watcher.prototype.update = function update () {
/* istanbul ignore else */
if (this.lazy) {
this.dirty = true;
} else if (this.sync) {
this.run();
} else {
queueWatcher(this);
}
};
继续看queueWatcher
function queueWatcher (watcher) {
var id = watcher.id;
if (has[id] == null) {
has[id] = true;
if (!flushing) {
queue.push(watcher);
} else {
var i = queue.length - 1;
while (i > index && queue[i].id > watcher.id) {
i--;
}
queue.splice(i + 1, 0, watcher);
}
// queue the flush
if (!waiting) {
waiting = true;
nextTick(flushSchedulerQueue);
}
}
}
没什么疑问,这里将观察者推入执行队列中,并且做了短时间内的去重优化(具有重复ID的作业将被跳过)
紧接着
function flushSchedulerQueue () {
...
callUpdatedHooks(updatedQueue);
}
function callUpdatedHooks (queue) {
var i = queue.length;
while (i--) {
var watcher = queue[i];
var vm = watcher.vm;
if (vm._watcher === watcher && vm._isMounted) {
callHook(vm, 'updated');
}
}
}
最后通过watcher内的调用Vue.protoype._update,再调用patch方法;
function patch () {
corePatch.apply(this, arguments);
this.$updateDataToMP();
}
function updateDataToMP () {
var page = getPage(this);
if (!page) {
return
}
var data = formatVmData(this);
diffData(this, data);
throttleSetData(page.setData.bind(page), data);
}
从而完成了数据的观察的更新;
A declarative, efficient, and flexible JavaScript library for building user interfaces.
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
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