vue watch

//我们想要一开始就让他执行最初绑定的函数
watch: {
  firstName: {
    handler(newName, oldName) {
      this.fullName = newName + ' ' + this.lastName;
    },
    // 代表在wacth里声明了firstName这个方法之后立即先去执行handler方法
    immediate: true
  }
}



//监听深层次结构obj:{name:'zs',id:1}
watch: {
  obj: {
    handler(newName, oldName) {
      console.log('obj.id changed');
    },
    immediate: true,
    deep: true
  }
}