计算属性return props报undefined

Question

props: ['item'],computed: {
        coinPrice () {            return this.item.currentPrice.toFixed(2)
        }
}

这里报this.item.currentPrice undefined，查了加载顺讯，props在computed之前，为什么会报undefined?
值可以出来，先报undefined后在出来

Answer 1

that result from data request is async，so occur undefined error in first time render