vue计算属性时v-for处理数组时遇到的一个bug问题

bonus_code: ['01', '19', '25', '26', '27', '33', '10']

ssqRed: function() {
return this.ssq.bonus_code.splice(0, 6)
},
ssqBlue: function() {
return this.ssq.bonus_code.splice(6, 7)
}

<em class="red-ball tac mr5 fl" v-for="(item, index) in ssqRed">{{ item }}</em>
<em class="blue-ball tac mr5 fl" v-for="(item, index) in ssqBlue">{{ item }}</em>

ssqRed: function() {
 return this.ssq.bonus_code.slice(0, 6)
},
ssqBlue: function() {
 return this.ssq.bonus_code.slice(6, 7)
}

<em v-for="(item, index) in ssq.bonus_code" :class="['tac','mr5','fl',index>5?'blue-ball':'red-ball']" >{{ item }}</em>

index>5?'blue-ball':'red-ball'