本节将看下初始化中的$options：
1 Vue.prototype._init = function (options?: Object) { 2 const vm: Component = this 3 // a uid 4 vm._uid = uid++ 5 6 // a flag to avoid this being observed 7 vm._isVue = true 8 // merge options 9 if (options && options._isComponent) { 10 // optimize internal component instantiation 11 // since dynamic options merging is pretty slow, and none of the 12 // internal component options needs special treatment. 13 initInternalComponent(vm, options) 14 } else { 15 vm.$options = mergeOptions( 16 // merge Vue.option 17 resolveConstructorOptions(vm.constructor), 18 // new Vue(data) data for object 19 options || {}, 20 // current instance 21 vm 22 ) 23 } 24 ……………………………… 25 }