<div id="classBind">
  <span :class="{warning:isWarning,safe:isSafe}" v-on:click="toggle">
  状态:{{alert}}{{isSafe}}
  </span>
</div>

//js
var app11=new Vue({
  el:'#classBind',
  data:{
    isWarning:true,
    alertList:['红色警报','警报解除'],
    alert:''
  },
  computed:{
    isSafe:function(){
      return !this.isWarning;
    }
  },
  methods:{
    toggle:function(){
      this.isWarning=!this.isWarning;
      this.alert= this.isWarning?this.alertList[0]:this.alertList[1];
    }
  }

});

.warning{
  color:#f24;
}
.safe{
  color:#42b983;
}

var app11=new Vue({
  el:'#classBind',
  data:{
    isWarning:true,
    alertList:['红色警报','警报解除'],
    alert:''
  },
  computed: {
    isSafe: function () {
      return !this.isWarning;
    },
    classObj:function(){
      return {
        warning: this.isWarning,
        safe:this.isSafe
      }
    }
  },
  methods:{
    toggle:function(){
      this.isWarning=!this.isWarning;
      this.alert= this.isWarning?this.alertList[0]:this.alertList[1];
    }
  }

});

<div v-bind:class="classArray" @click="removeClass()">去掉class</div>

data: {
classArray:["big",'red']
}
methods:{
removeClass:function(){

　　this.classArray.pop();
}
}

.big{
  font-size:2rem;
}
.red{
   color:red;  
}

<div id="styleBind">
  <span :style="{color:theColor,fontSize:theSize+'px'}" @click="bigger">styleBind</span>
</div>

var app12=new Vue({
  el:'#styleBind',
  data:{
    theColor:'red',
    theSize:14
  },
  methods:{
    bigger:function(){
      this.theSize+=2;
    }
  }

});