上一节看完《Vue源码思维导图-------------Vue 构造函数、原型、静态属性和方法》，这节将会以new Vue()为入口，大体看下 this._init()要做的事情。
function Vue (options) {
if (process.env.NODE_ENV !== 'production' &&
!(this instanceof Vue)
) {
warn('Vue is a constructor and should be called with the `new` keyword')
}
this._init(options)
}
initMixin(Vue)
stateMixin(Vue)
eventsMixin(Vue)
lifecycleMixin(Vue)
renderMixin(Vue)
export default Vue
下边解开_init的面纱
export function initMixin (Vue: Class<Component>) {
Vue.prototype._init = function (options?: Object) {
const vm: Component = this
// a uid
vm._uid = uid++
let startTag, endTag
/* istanbul ignore if */
if (process.env.NODE_ENV !== 'production' && config.performance && mark) {
startTag = `vue-perf-start:${vm._uid}`
endTag = `vue-perf-end:${vm._uid}`
mark(startTag)
}
// a flag to avoid this being observed
vm._isVue = true
// merge options
if (options && options._isComponent) {
// optimize internal component instantiation
// since dynamic options merging is pretty slow, and none of the
// internal component options needs special treatment.
initInternalComponent(vm, options)
} else {
vm.$options = mergeOptions(
resolveConstructorOptions(vm.constructor),
options || {},
vm
)
}
/* istanbul ignore else */
if (process.env.NODE_ENV !== 'production') {
initProxy(vm)
} else {
vm._renderProxy = vm
}
// expose real self
vm._self = vm
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')
/* istanbul ignore if */
if (process.env.NODE_ENV !== 'production' && config.performance && mark) {
vm._name = formatComponentName(vm, false)
mark(endTag)
measure(`vue ${vm._name} init`, startTag, endTag)
}
if (vm.$options.el) {
vm.$mount(vm.$options.el)
}
}
}
总结思维导图如下：
高清原图地址：https://github.com/huashuaipeng/vue--/blob/master/Vue_init.png
// Vue.prototype._init
vm._uid = uid++ // 每个Vue实例都拥有一个唯一的 id
vm._isVue = true // 这个表示用于避免Vue实例对象被观测(observed)
vm.$options // 当前 Vue 实例的初始化选项，注意：这是经过 mergeOptions() 后的
vm._renderProxy = vm // 渲染函数作用域代理
vm._self = vm // 实例本身 // initLifecycle(vm) src/core/instance/lifecycle.js **************************************************
vm.$parent = parent
vm.$root = parent ? parent.$root : vm vm.$children = []
vm.$refs = {} vm._watcher = null
vm._inactive = null
vm._directInactive = false
vm._isMounted = false
vm._isDestroyed = false
vm._isBeingDestroyed = false // initEvents(vm) src/core/instance/events.js **************************************************
vm._events = Object.create(null)
vm._hasHookEvent = false // initRender(vm) src/core/instance/render.js **************************************************
vm._vnode = null // the root of the child tree
vm._staticTrees = null // v-once cached trees vm.$vnode
vm.$slots
vm.$scopedSlots vm._c
vm.$createElement vm.$attrs
vm.$listeners // initState(vm) src/core/instance/state.js **************************************************
vm._watchers = []
vm._data
代码参考：
https://github.com/vuejs/vue/tree/dev/src/core/instance