尝试在React Native中在平面列表内声明变量时出现意外令牌 [英] unexpected token when trying to declare a variable inside flatlist in react native
问题描述
我正在尝试在React Native的FlatList组件中声明一个变量 但是当我声明它时,我得到了意外的令牌.
i'm trying to declare an variable inside the FlatList component in React Native But i get unexpected token, when i do declare it.
const FixturesScreen = ({ navigation }) => (
<ScrollView style={styles.container}>
<FlatList
data={clubData.data.clubs}
renderItem={({ item }) => (
let fixture = item.name //unexpected token
<View>
<View>
<Text style={styles.itemTitle}>{item.name}</Text>
<ScrollView horizontal>
<Text style={styles.listItem}>{fixture}</Text>
</ScrollView>
</View>
</View>
)
}
/>
</ScrollView>
)
这是我完整的FixturesScreen cdoe
here is my full FixturesScreen cdoe
import React from 'react'
import { View, Text, FlatList, ScrollView, StyleSheet } from 'react-native'
import Ionicons from 'react-native-vector-icons/Ionicons'
import clubData from '../../clubData'
const styles = StyleSheet.create({
container: {
backgroundColor: '#4BABF4',
},
itemTitle: {
color: 'black',
fontSize: 20,
marginTop: 20,
marginBottom: 10,
marginLeft: 15,
},
listItem: {
color: '#FFFFFF',
fontSize: 18,
textAlign: 'center',
marginRight: 15,
marginLeft: 15,
backgroundColor: '#77BEF5',
width: 120,
paddingVertical: 10,
},
})
const CURRENTTGAMEWEEK = 30
const i = CURRENTTGAMEWEEK
const nxt1 = i + 1
const nxt2 = nxt1 + 2
const nxt3 = nxt2 + 1
const nxt4 = nxt3 + 1
const nxt5 = nxt4 + 1
// let fixture
// const team = clubData.data.clubs[0].name
// const hTeam = clubData.data.clubs[0].fixtures[0].homeTeam
// const hTeamShort = clubData.data.clubs[0].fixtures[0].homeTeamShort
// const aTeamShort = clubData.data.clubs[0].fixtures[0].awayTeamShort
//
// if (team === hTeam) // working
// fixture = aTeamShort
// else
// fixture = hTeamShort
console.log(`Now is playing ${fixture}`)
const FixturesScreen = ({ navigation }) => (
<ScrollView style={styles.container}>
<FlatList
data={clubData.data.clubs}
renderItem={({ item }) => (
let fixture = item.name
<View>
<View>
<Text style={styles.itemTitle}>{item.name}</Text>
<ScrollView horizontal>
<Text style={styles.listItem}>{fixture}</Text>
</ScrollView>
</View>
</View>
)
}
/>
</ScrollView>
)
FixturesScreen.navigationOptions = {
tabBarTestIDProps: {
testID: 'TEST_ID_HOME',
accessibilityLabel: 'TEST_ID_HOME_ACLBL',
},
tabBarLabel: 'Main',
tabBarIcon: ({ tintColor, focused }) => (
<Ionicons
name={focused ? 'ios-home' : 'ios-home-outline'}
size={26}
style={{ color: tintColor }}
/>
),
}
export default FixturesScreen
所以基本上我想做的是在平面列表中声明homeTeam,awayTeam和Fixture,因此我可以在平面列表中进行if/else条件渲染.我可以在flatlist组件之外实现该功能,但这是不对的,因为我无法一次比较所有对象.
So basically what i'm trying to do is declare homeTeam, awayTeam and Fixture inside the flatlist, so i can do an if/else conditional rendering inside the flatlist. I can achieve that outside the flatlist component but it is not right, because i can not compare all objects at once.
推荐答案
同时使用箭头功能 () => ('someValue')
是() => { return 'someValue'}
的快捷方式.
While using arrow functions () => ('someValue')
is a shortcut for () => { return 'someValue'}
.
(param1, param2, …, paramN) => { statements }
(param1, param2, …, paramN) => expression
// equivalent to: (param1, param2, …, paramN) => { return expression; }
// Parentheses are optional when there's only one parameter name:
(singleParam) => { statements }
singleParam => { statements }
// A function with no parameters should be written with a pair of parentheses.
() => { statements }
// Parenthesize the body of function to return an object literal expression:
params => ({foo: bar})
因此,如果要在返回值之前运行一些代码,则应执行以下操作;
So if you want to run some code before returning a value you should do like below;
const FixturesScreen = ({ navigation }) => (
<ScrollView style={styles.container}>
<FlatList
data={clubData.data.clubs}
renderItem={({ item }) => { //change to curly braces
let fixture = item.name;
// do something here
return (
<View>
<View>
<Text style={styles.itemTitle}>{item.name}</Text>
<ScrollView horizontal>
<Text style={styles.listItem}>{fixture}</Text>
</ScrollView>
</View>
</View>
);
}}
/>
</ScrollView>
)
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