Once again about the update mechanism

[suntong]

Following up on #146,

I've verified that the console.log(this.data.weather) is correct.
The next this.update() should update the view right?

If I comment out the this.update() statement here:

westore/packages/westore-example/stores/user-store.js

Lines 13 to 20 in 4bcdccc

	this.user = new User({
	onUserInfoLoaded: () => {
	this.data.motto = this.user.motto
	this.data.userInfo = this.user.userInfo
	this.update()
	}
	})
	}

The update is still happening, which seems odd to me.
How the whole update mechanism works please?

去掉 this.update() 语句 按道理就应该不会update，可为什么又update了呢？