watcher
SRC \platforms\web\ Runtime \index.js the last mountComponent method to be used in the registration of the $mount method
mountComponent()
In this method we find new Watcher, which is where the Wather instance is created, one Watcher for each component/instance
updateComponent
vm._update(vm._render(), hydrating)
expOrFn
this.getter
this.getter
updateComponent()
_update
vm._update(vm._render(), hydrating)
_render
Dep
The _render function is bound to trigger the get of the data attribute, SRC \core\observer\index.js can be found in dep.depend() when get is triggered, and dep.target.adddep (this)
PushTarget () does define dep.target, so the data attribute does not fire dep.target every time when get is triggered.
