我想自定义一个点击事件实现切换效果，可是setData一直报错，重新定义一个变量that，用that.setData也还在报错

<div id="tableft" :class="currentTab === 0 ? 'tab-active': ''" @click="switchTab">a</div>
<div id="tabright" :class="currentTab === 1 ? 'tab-active': ''" @click="switchTab">b</div>

switchTab(e) {
        let tab = e.currentTarget.id
        let that = this
        console.log(e)
        if (tab === 'tableft') {
        that.setData({ currentTab : 0 })
        } else if (tab === 'tabright') {
        that.setData({
            currentTab: 1
        })
        }
    }