undefined 不是一个函数（靠近'...datas.map ....'）

Question

This is my data

[{"size":"Small","price":"90"},{"size":"Large","price":"180"},{"size":"Extra Large","price":"200"}]

and this is my code

const route = useRoute();
const [datas, setDatas] = useState([]);

useEffect(() => {
   setDatas(route.params.item_sizes);   
},[])

const ItemSizes = () => {
        if(datas.length > 0)
        {
            console.log("Item size data: ", datas); //for debugging purposes
            return(
                <View>
                    {datas.map((data,key) => (
                        <View key={key}>
                            <View style={{flex:0.2}}>
                                <MaterialCommunityIcons name={"radiobox-blank"} size={20} color={'gray'}/>
                                {/* <Text style={{fontSize:16, fontWeight:'bold'}}>Icon</Text> */}
                            </View>
                            <View style={{flex:1}}>
                                <Text style={{fontSize:16, fontWeight:'bold'}}>{data.size}</Text>
                            </View>
                            <View style={{flex:1, flexDirection:'row-reverse'}}>
                                <Text style={{fontSize:16, fontWeight:'bold'}}>{data.price}</Text>
                            </View>
                        </View>
                        ))}
                </View>
            )
        }
    }

I call it from my view like this

return (
    <View>
       {ItemSizes()}
    </View>
)

So after I checked there's a data on datas so why it is undefined? Please do explain why it is returning me undefined even though there's a data?? Thank you

Answer 1

Check if the data you are setting is an array or string. If it's string set it like below by parsing

 setData(JSON.parse(route.params.item_sizes));