写了上一篇文章后，不禁的想，主流程去哪了？我下一步该做那些呢？既然没有找到方向，不如我们就看一下src/core/instance/index.js里其他方法的调用，都干了些什么事情
今天我们针对上边文章中src/core/instance/index.js源码的其他部分做出补充，看看其他部分都做了些什么，只是宏观了解，深层次的理解，我们后期一起研究 上面文章中_init调用是在initMixin中声明的，那么stateMixin、eventsMixin、lifecycleMixin、renderMixin又初始化了些什么（src/core/instance/index.js----针对这个js进行了解）
以下是stateMixin源码
export function stateMixin (Vue: Class<Component>) {
// flow somehow has problems with directly declared definition object
// when using Object.defineProperty, so we have to procedurally build up
// the object here.
const = {}
dataDef.get = function () { return this._data }
const propsDef = {}
propsDef.get = function () { return this._props }
if (process.env.NODE_ENV !== 'production') {
dataDef.set = function () {
warn(
'Avoid replacing instance root $data. ' +
'Use nested data properties instead.',
this
)
}
propsDef.set = function () {
warn(`$props is readonly.`, this)
}
}
//看到这里，大概知道这里主要是针对$data和$props了
//进行数据劫持，我把defineProperty的相关知识点放在下面了
//对$data、$props进行了数据劫持
Object.defineProperty(Vue.prototype, '$data', dataDef)
Object.defineProperty(Vue.prototype, '$props', propsDef)
//这不是我们熟悉的 this.$set嘛
Vue.prototype.$set = set
Vue.prototype.$delete = del
//定义了$watch，具体功能不在本章研究范围了，先过，后期再深入了解
Vue.prototype.$watch = function (
expOrFn: string | Function,
cb: any,
options?: Object
): Function {
const vm: Component = this
if (isPlainObject(cb)) {
return createWatcher(vm, expOrFn, cb, options)
}
options = options || {}
options.user = true
const watcher = new Watcher(vm, expOrFn, cb, options)
if (options.immediate) {
const info = `callback for immediate watcher "${watcher.expression}"`
pushTarget()
invokeWithErrorHandling(cb, vm, [watcher.value], vm, info)
popTarget()
}
return function unwatchFn () {
watcher.teardown()
}
}
}
数据劫持相关代码
// 数据劫持的核心属性
Object.defineProperty(obj, 'name', {
enumerable: true,
configurable: true,
get() {
// 每次获取对象的这个属性的时候，就会被这个get方法给劫持到
console.log('get执行了')
},
// 每次设置这个对象的属性的时候，就会被set方法劫持到
// 设置的值也会劫持到
set(newValue) {
console.log('set方法执行了');
console.log(newValue)
\
}
})
小结：只是对props进行了数据劫持；定义了delete，$watch
以下是eventsMixin的源码
export function eventsMixin (Vue: Class<Component>) {
const hookRE = /^hook:/
Vue.prototype.$on = function (event: string | Array<string>, fn: Function): Component {
const vm: Component = this
if (Array.isArray(event)) {
for (let i = 0, l = event.length; i < l; i++) {
vm.$on(event[i], fn)
}
} else {
(vm._events[event] || (vm._events[event] = [])).push(fn)
// optimize hook:event cost by using a boolean flag marked at registration
// instead of a hash lookup
if (hookRE.test(event)) {
vm._hasHookEvent = true
}
}
return vm
}
Vue.prototype.$once = function (event: string, fn: Function): Component {
const vm: Component = this
function on () {
vm.$off(event, on)
fn.apply(vm, arguments)
}
on.fn = fn
vm.$on(event, on)
return vm
}
Vue.prototype.$off = function (event?: string | Array<string>, fn?: Function): Component {
const vm: Component = this
// all
if (!arguments.length) {
vm._events = Object.create(null)
return vm
}
// array of events
if (Array.isArray(event)) {
for (let i = 0, l = event.length; i < l; i++) {
vm.$off(event[i], fn)
}
return vm
}
// specific event
const cbs = vm._events[event]
if (!cbs) {
return vm
}
if (!fn) {
vm._events[event] = null
return vm
}
// specific handler
let cb
let i = cbs.length
while (i--) {
cb = cbs[i]
if (cb === fn || cb.fn === fn) {
cbs.splice(i, 1)
break
}
}
return vm
}
Vue.prototype.$emit = function (event: string): Component {
const vm: Component = this
if (process.env.NODE_ENV !== 'production') {
const lowerCaseEvent = event.toLowerCase()
if (lowerCaseEvent !== event && vm._events[lowerCaseEvent]) {
tip(
`Event "${lowerCaseEvent}" is emitted in component ` +
`${formatComponentName(vm)} but the handler is registered for "${event}". ` +
`Note that HTML attributes are case-insensitive and you cannot use ` +
`v-on to listen to camelCase events when using in-DOM templates. ` +
`You should probably use "${hyphenate(event)}" instead of "${event}".`
)
}
}
let cbs = vm._events[event]
if (cbs) {
cbs = cbs.length > 1 ? toArray(cbs) : cbs
const args = toArray(arguments, 1)
const info = `event handler for "${event}"`
for (let i = 0, l = cbs.length; i < l; i++) {
invokeWithErrorHandling(cbs[i], vm, args, vm, info)
}
}
return vm
}
}
小结：只是定义了：once，emit等方法，相信大家平时对emit很熟悉。这里暂时只是简单的了解。
以下是lifecycleMixin的源码(lifecycle.js文件)
export function lifecycleMixin (Vue: Class<Component>) {
Vue.prototype._update = function (vnode: VNode, hydrating?: boolean) {
const vm: Component = this
const prevEl = vm.$el
const prevVnode = vm._vnode
const restoreActiveInstance = setActiveInstance(vm)
vm._vnode = vnode
// Vue.prototype.__patch__ is injected in entry points
// based on the rendering backend used.
if (!prevVnode) {
// initial render
vm.$el = vm.__patch__(vm.$el, vnode, hydrating, false /* removeOnly */)
} else {
// updates
vm.$el = vm.__patch__(prevVnode, vnode)
}
restoreActiveInstance()
// update __vue__ reference
if (prevEl) {
prevEl.__vue__ = null
}
if (vm.$el) {
vm.$el.__vue__ = vm
}
// if parent is an HOC, update its $el as well
if (vm.$vnode && vm.$parent && vm.$vnode === vm.$parent._vnode) {
vm.$parent.$el = vm.$el
}
// updated hook is called by the scheduler to ensure that children are
// updated in a parent's updated hook.
}
Vue.prototype.$forceUpdate = function () {
const vm: Component = this
if (vm._watcher) {
vm._watcher.update()
}
}
Vue.prototype.$destroy = function () {
const vm: Component = this
if (vm._isBeingDestroyed) {
return
}
callHook(vm, 'beforeDestroy')
vm._isBeingDestroyed = true
// remove self from parent
const parent = vm.$parent
if (parent && !parent._isBeingDestroyed && !vm.$options.abstract) {
remove(parent.$children, vm)
}
// teardown watchers
if (vm._watcher) {
vm._watcher.teardown()
}
let i = vm._watchers.length
while (i--) {
vm._watchers[i].teardown()
}
// remove reference from data ob
// frozen object may not have observer.
if (vm._data.__ob__) {
vm._data.__ob__.vmCount--
}
// call the last hook...
vm._isDestroyed = true
// invoke destroy hooks on current rendered tree
vm.__patch__(vm._vnode, null)
// fire destroyed hook
callHook(vm, 'destroyed')
// turn off all instance listeners.
vm.$off()
// remove __vue__ reference
if (vm.$el) {
vm.$el.__vue__ = null
}
// release circular reference (#6759)
if (vm.$vnode) {
vm.$vnode.parent = null
}
}
}
小结：看上去只是对_update、destroy等做了初始化的定义
以下是renderMixin的源码
export function renderMixin (Vue: Class<Component>) {
// install runtime convenience helpers
installRenderHelpers(Vue.prototype)
Vue.prototype.$nextTick = function (fn: Function) {
return nextTick(fn, this)
}
Vue.prototype._render = function (): VNode {
const vm: Component = this
const { render, _parentVnode } = vm.$options
if (_parentVnode) {
vm.$scopedSlots = normalizeScopedSlots(
_parentVnode.data.scopedSlots,
vm.$slots,
vm.$scopedSlots
)
}
// set parent vnode. this allows render functions to have access
// to the data on the placeholder node.
vm.$vnode = _parentVnode
// render self
let vnode
try {
// There's no need to maintain a stack because all render fns are called
// separately from one another. Nested component's render fns are called
// when parent component is patched.
currentRenderingInstance = vm
vnode = render.call(vm._renderProxy, vm.$createElement)
} catch (e) {
handleError(e, vm, `render`)
// return error render result,
// or previous vnode to prevent render error causing blank component
/* istanbul ignore else */
if (process.env.NODE_ENV !== 'production' && vm.$options.renderError) {
try {
vnode = vm.$options.renderError.call(vm._renderProxy, vm.$createElement, e)
} catch (e) {
handleError(e, vm, `renderError`)
vnode = vm._vnode
}
} else {
vnode = vm._vnode
}
} finally {
currentRenderingInstance = null
}
// if the returned array contains only a single node, allow it
if (Array.isArray(vnode) && vnode.length === 1) {
vnode = vnode[0]
}
// return empty vnode in case the render function errored out
if (!(vnode instanceof VNode)) {
if (process.env.NODE_ENV !== 'production' && Array.isArray(vnode)) {
warn(
'Multiple root nodes returned from render function. Render function ' +
'should return a single root node.',
vm
)
}
vnode = createEmptyVNode()
}
// set parent
vnode.parent = _parentVnode
return vnode
}
}
小结：renderMixin对$nextTick，_rende进行了定义
总结：stateMixin、eventsMixin、lifecycleMixin、renderMixin分别功能如下
1.stateMixin：只是对$data、$props进行了数据劫持；定义了$set，$delete，$watch
2.eventsMixin：只是定义了：$on，$once，$off，$emit等方法
3.lifecycleMixin：只是对_update、$forceUpdate、$destroy等做了初始化的定义
4.renderMixin：只是对$nextTick，_rende进行了定义
前期声明了大量的方法，为后期服务；
写到这里，感觉还有好多东西需要探索！！！，个人学习源码经历，有不对的地方欢迎大家指正
