If语句:SyntaxError意外的令牌，应为

Question

在react native中，我试图放入一些代码，这些代码将在按下按钮后加载字体。if语句得到一个错误(第38:6行)，上面写着，Unexpected token，expected，(38:6)。我不知道为什么会发生这种情况，也不知道把它想要的逗号放在哪里，或者问题是否是其他原因。

错误消息

38号线

更新代码：

import React, { Component } from 'react';
import { StyleSheet, Text, View, Image, TextInput, ScrollView, TouchableHighlight, Button } from 'react-native';
import { Font } from 'expo';
var fontLoaded = false;
export default class App extends React.Component {
componentDidMount() {
Expo.Font.loadAsync({
'Cabin-Regular-TTF': require('./Cabin-Regular-TTF.ttf'),
});

}
constructor(props) {
super(props);
this.state = { postInput: ""}
}

render() {
return (
<View style={styles.container}>
<View style={{width: 1, height: 30, backgroundColor: '#e8e8e8'}} />
<Button
onPress={() => this.setState({ fontLoaded: true })}
title="Press Me To Load the App After 15 Seconds!"
color="#841584"
accessibilityLabel="Wait 15 seconds and then press me to load the font!"
/>
</View>

{fontLoaded ? (
<View style={styles.container}>
<Text style={{ fontFamily: 'Cabin-Regular-TTF', fontSize: 16 }}>
Whats on your mind? Create a post!
</Text>  
<TextInput>
style={{height:40, width: 320, borderColor: '#303030', borderWidth: 1}}
onChangeText={(postInput)=>this.setState({postInput})}
value={this.state.postInput}    
</TextInput>
<ScrollView>
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
</ScrollView>
</View>) : (null) }
);
}

const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: '#e8e8e8',
alignItems: 'center',
justifyContent: 'center'
},
});

Answer 1

组件的模板必须只有一个顶级容器。所以我把你的组件放在一个封闭标签之间，错误就消失了：

import React, { Component } from 'react';
import { StyleSheet, Text, View, Image, TextInput, ScrollView, TouchableHighlight, Button } from 'react-native';
import { Font } from 'expo';
var fontLoaded = false;
export default class App extends React.Component {
componentDidMount() {
Expo.Font.loadAsync({
'Cabin-Regular-TTF': require('./Cabin-Regular-TTF.ttf'),
});

}
constructor(props) {
super(props);
this.state = { postInput: ""}
}
render() {
return (
<View>
<View style={styles.container}>
<View style={{width: 1, height: 30, backgroundColor: '#e8e8e8'}} />
<Button
onPress={this.setState({ fontLoaded: true })}
title="Press Me To Load the App After 15 Seconds!"
color="#841584"
accessibilityLabel="Wait 15 seconds and then press me to load the font!"
/>
</View>

{fontLoaded ? (
<View style={styles.container}>
<Text style={{ fontFamily: 'Cabin-Regular-TTF', fontSize: 16 }}>
Whats on your mind? Create a post!
</Text>  
<TextInput>
style={{height:40, width: 320, borderColor: '#303030', borderWidth: 1}}
onChangeText={(postInput)=>this.setState({postInput})}
value={this.state.postInput}    
</TextInput>
<ScrollView>
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
</ScrollView>
</View>) : (null) }
</View>
);
}
} // missing one!
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: '#e8e8e8',
alignItems: 'center',
justifyContent: 'center'
},
});

此外，您还错过了在类定义结束时关闭}。我在上面加了一条评论。

Answer 2

尝试

{
fontLoaded && (
<View style={styles.container}>
....
</View>
)
}

我在你的onPress上也看到了问题——应该是

onPress={() => this.setState({ fontLoaded: true })}

Answer 3

为什么不重构代码，并将所有scrollView代码移到新函数中，例如：

renderScrollWrapper() {
retun(
<View style={styles.container}>
<Text style={{ fontFamily: 'Cabin-Regular-TTF', fontSize: 16 }}>
Whats on your mind? Create a post!
</Text>  
<TextInput>
style={{height:40, width: 320, borderColor: '#303030', borderWidth: 1}}
onChangeText={(postInput)=>this.setState({postInput})}
value={this.state.postInput}    
</TextInput>
<ScrollView>
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
<View style={{width: 300, height: 250, backgroundColor: '#1daff1'}} />
<View style={{width: 300, height: 40, backgroundColor: '#147aa8'}} />
<View style={{width: 1, height: 6, backgroundColor: '#e8e8e8'}} />
</ScrollView>
</View>);
}

然后将渲染方法更改为

render() {
return (
<View>
<View style={styles.container}>
<View style={{width: 1, height: 30, backgroundColor: '#e8e8e8'}} />
<Button
onPress={this.setState({ fontLoaded: true })}
title="Press Me To Load the App After 15 Seconds!"
color="#841584"
accessibilityLabel="Wait 15 seconds and then press me to load the font!"
/>
</View>
{fontLoaded ? {this.renderScrollWrapper()} : (null) }
</View>
);

}