Question

我有这个简单的脚本，每隔几分钟生成一个随机数，每次rand不等于我想改变其背景颜色之前的那个。可能？所以随机数生成1,1,3，当它达到3我想要高亮背景。感谢

new Vue({
  el: '#app',
  data: {
    rand: 0
  },
  mounted : function(){
   var me = this;
    setInterval(function(){
        me.rand = Math.floor(Math.random() * 4) + 1 ;
      me.$forceUpdate();
    },1000)
  }
})


<div id="app">
  <p>{{rand}}</p>
</div>

Answer 1

创建一个data属性来存储更新后的值是否与当前值不同，并将background-color绑定到该值：

＆＃13;

new Vue({
  el: '#app',
  data() {
    return { 
      rand: 0,
      diff: false
    }
  },
  mounted() {
    setInterval(() => {
      let rand = Math.floor(Math.random() * 4) + 1 ;
      this.diff = rand !== this.rand;
      this.rand = rand;
    }, 1000);
  }
})

＆＃13;

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.2/vue.min.js"></script>
<div id="app">
  <p :style="{ 'background-color': (diff) ? 'gold' : 'initial' }">{{rand}}</p>
</div>

＆＃13;

Answer 2

一个很好的方法是使用具有类绑定的观察者。看看这个 js 小提琴：https://jsfiddle.net/omarjebari/wjf8qbt0/18/

<div id="app">
   <div class="random-element" v-bind:class="{ active: isChanged }">{{ rand }}</div>
</div>
<script>

    new Vue({
        el: "#app",
        data: {
            rand: 0,
            isChanged: false,
        },
        mounted : function(){
            setInterval(() => {
                this.rand = Math.floor(Math.random() * 4) + 1;
            }, 1000);
        },
        watch: {
            rand(newVal, oldVal) {
                console.log(`${newVal} vs ${oldVal}`);
                if (newVal !== oldVal) {
                    this.isChanged = true;
                    setTimeout(() => {
                        this.isChanged = false;
                    }, 300);
                }
            }
        },
    })
</script>
<style>
    div.random-element {
        height: 30px;
        color: black;
        padding: 5px;
    }

    div.active {
        background-color: red;
    }
</style>

Vue js，检测何时更改值以突出显示其文本

2 个答案: