vue中watch数组或者对象

1、普通的watch

data() {
    return {
        frontPoints: 0   
    }
},
watch: {
    frontPoints(newValue, oldValue) {
        console.log(newValue)
    }
}


2、数组的watch

data() {
    return {
        winChips: new Array(11).fill(0)  
    }
},
watch: {
  winChips: {
    handler(newValue, oldValue) {
      for (let i = 0; i < newValue.length; i++) {
        if (oldValue[i] != newValue[i]) {
          console.log(newValue)
        }
      }
    },
    deep: true
  }
}


3、对象的watch


data() {
  return {
    bet: {
      pokerState: 53,
      pokerHistory: 'local'
    }  
    }
},
watch: {
  bet: {
    handler(newValue, oldValue) {
      console.log(newValue)
    },
    deep: true
  }
}


tips: 只要bet中的属性发生变化(可被监测到的),便会执行handler函数;
如果想监测具体的属性变化,如pokerHistory变化时,才执行handler函数,则可以利用计算属性computed做中间层。
事例如下:

4、对象具体属性的watch[活用computed]


data() {
  return {
    bet: {
      pokerState: 53,
      pokerHistory: 'local'
    }  
    }
},
computed: {
  pokerHistory() {
    return this.bet.pokerHistory
  }
},
watch: {
  pokerHistory(newValue, oldValue) {
    console.log(newValue)
  }
}


posted @ 2019-08-19 15:56  浪里小白龙呼呼呼  阅读(17364)  评论(2编辑  收藏  举报