Question

我正在使用雅虎天气，大约有47种天气状况，从0到47，每个数字代表天气状况。

我想获得4天，今天和接下来3天的条件，因此如果我为每个语句使用switch语句，将会有很长的switch语句代码。

我的代码现在适用于今天条件：

var src = ""; //This variable will contain an icon that represents the weather condition.

switch(todayCondition){ //todayCondition is today condition it's in the range [0-47]

    case "0":
        src = 'storm.svg';
    break;
    ........
    ........
    case  "47":
        src = 'rain.svg';
    break;

}

document.getElementById('todayWeatherIcon').src = src;

html：

 <img id = 'todayWeatherIcon' />

接下来的3天条件中还有3个其他变量也将从0-47开始，并且根据数字将具有相同的图标。

如何在不重复相同代码的情况下为其他3个变量做同样的事情？

Answer 1

不需要多个switch语句，因为你有一个固定的文件名，文件名中的每个天气条件号都可以这样做

var src = "";
// concatenate todayCondition with the rest of the file name
src = "condition" + todayCondition + "Img.png";

document.getElementById('todayWeatherIcon').src = src;

注意：只有在知道文件名称在不久的将来不会改变时才应该这样做

Answer 2

您可以像这样设置条件

render() { // If loading, render activity indicator if (this.props.isLoadingPosts) { return ( <View style={commonStyles.center}> <ActivityIndicator /> </View> ); } // Otherwise render posts return ( <View> <FlatList style={styles.fullHeight} data={this.props.data} extraData={this.props.loadingMore} keyboardShouldPersistTaps='always' keyExtractor={(item, index) => index.toString()} ItemSeparatorComponent={this.renderSeparator} ListFooterComponent={this.renderFooter} refreshing={this.props.refreshing} onRefresh={this.onRefresh} onEndReached={this.onEndReached} onEndReachedThreshold={0.5} renderItem={({ item }) => ( <ListItem item={item} onPressItem={() => this.showPost(item)} navigator={this.props.navigator} /> )} /> </View> ); }

Answer 3

您应该只使用一个功能：

function getIcon(weatherCondition) 
{
    var src = ""; //This variable will contain an icon that represents the weather condition.
    switch(weatherCondition){ //weatherCondition is the weather condition it's in the range [0-47]
        case "0":
            src = 'storm.svg';
            break;
        ........
        ........
        case  "47":
            src = 'rain.svg';
            break;
    }
    return src;
}

var day1Condition = getIcon(todayCondition);
var day2Condition = getIcon(tomorrowCondition);
...
document.getElementById('todayWeatherIcon').src = day1Condition;
document.getElementById('tomorrowWeatherIcon').src = day2Condition;
...

Answer 4

如果图像名称都不同，那么最好使用字符串数组，如下所示：

var images = ["cloudy.svg", "sunny.svg", "rainy.svg"];

// Arrays are designed to work with numeric index values:
console.log(images[0]);
console.log(images[1]);
console.log(images[2]);
console.log("--------------")

// Javascript also accepts "numeric strings" as array index values:
console.log(images["0"]);
console.log(images["2"]);
console.log("--------------")

// Or using a variable, this is the closest to what you need to do:
var todayCondition = "1";
var src = images[todayCondition];
console.log(src);

如何使用带有多个变量的开关？

4 个答案: