vue中watch的实际开发学习笔记

  watch:{  // 当这个workType发生改变时，就是1个数据的改变，就会影响到type5和foll的改变
    'queryParams.workType':function (newName,oldName){
      if(newName==1){
        this.type5 = this.type3,
        this.foll = true
      }else if(newName==2){
        this.type5 = this.type4,
        this.foll = false
      }
    }
  },

  watch: {
    isLoading (newVal, oldVal) { //1. 原来的值，和现在的值，是否有变化，如果有变化，触发这个函数
      console.log('2 isLoading newVal is ', newVal, ' , oldVal is ', oldVal)
 
      //2. 当加载完成时, 还需要判断用户是否已登录
      const username = getLoginedUsername(this.$store)
      if (username != undefined && username != null) {
        // 已登录时, 跳转首页
        toHomePage(this)
      }
    }
  },
 
  computed: {
    isLoading () {
      return isLoading(this.$store)
    }
  },
 
import { isLoading, getLoginedUsername } from 'utils/utils'

 data() {
    return {
      verifyData: this.propData,
      editBoxShow: false,
 
      type3: [{
        worksRegion: '0',
        label: '牛奶'
      },{
        worksRegion:"1",
        label: "面包"
      },
        {
          worksRegion:"3",
          label: "水果"
        }
      ],
      type4: [{
        worksRegion: '0',
        label: '炸鸡'
      },{
        worksRegion:"1",
        label: "汉堡"
      },{
          worksRegion:"2",
          label: "可乐"
        },
        {
          worksRegion:"3",
          label: "北京烤鸭"
        }
      ],
      type5:[],
     
      queryParams:{
        id:"",
        workType:'',//1开发 , 2 测试 
        foll:true
      },
 
    };
}

  watch:{  // 当这个workType发生改变时，就是1个数据的改变，就会影响到type5和foll的改变
    'queryParams.workType':function (newName,oldName){
      if(newName==1){
        this.type5 = this.type3,
        this.foll = true
      }else if(newName==2){
        this.type5 = this.type4,
        this.foll = false
      }
    }
  },

说明：
 
handler: 固定方法触发
deep: 开启深度监听
immediate: 页面初始化时handler立即执行一次
 
  data(){
    return {
      user: {
        userNo: "",
        sex: ""
      }
    }
  },
 
  // 监听整对象
  watch: {
        // 监听整个对象，对象里的每个属性值的变化都会执行handler，执行后获取的 newVal 值和 oldVal 值是一样的
    user: {
      handler(newVal, oldVal){
        console.log(newVal, oldVal);
      },
      deep: true,
      immediate: true
    }
  }
 
 watch: {
       // 监听对象的某个属性，被监听的属性值发生变化就会执行函数，但获取的 newVal 值和 oldVal 值不一样
    'user.userNo': {
      handler(newVal, oldVal){
        console.log(newVal, oldVal);
      },
      deep: true,
      immediate: true
    }
  }
 
 

  watch: {
    traysNos (newVal, oldVal) {
      if ((newVal && !oldVal) || (newVal && oldVal && newVal !== oldVal)) {
        this.filterDeliverysOutLists = []
        this.deliverysOutsList = this.fullsDeliverysOutsLists
      }
    }
  },

   data () {
    return {
      loading: false,
      submitsCheck: true,
    }
  },
 
 watch: {
    'order.traysNos' (val) {
      if (val == null || val == '') {
        this.submitsCheck = true
      } else if (val) {
        this.submitsCheck = false
      }
    }
  },
 

  watch: {
    reservesNo (newVal, oldVal) {
      if ((newVal && !oldVal) || (newVal && oldVal && newVal !== oldVal)) {
        this.reservesNo = newVal // 获取到新值
        this.$router.replace({  // 跳转，注意，这种跳转，是不可以回退的
          query: {
            reservesNo: this.reservesNo  // 传新值
          }
        })
        this.findOrderNo()  // 执行其他的函数
      }
    }
  },

<script>
export default {
  name: "Home",
  data() {
    return {
      text: ""
    };
  },
  watch: {
    text(newVal, oldVal) {
      
    }
  },
};
</script>