JavaScript基础

// 使用async/await改写Promise
async function getUserData(userId) {
    try {
        const response = await fetch(`/api/users/${userId}`);
        const userData = await response.json();
        
        // 等待多个异步操作
        const [posts, comments] = await Promise.all([
            fetch(`/api/posts?user=${userId}`).then(r => r.json()),
            fetch(`/api/comments?user=${userId}`).then(r => r.json())
        ]);
        
        return { userData, posts, comments };
    } catch (error) {
        console.error('获取用户数据失败:', error);
        throw error;
    }
}

// 使用async函数
getUserData(123)
    .then(data => console.log(data))
    .catch(error => console.error(error));

// 错误处理最佳实践
async function loadData() {
    try {
        // 设置超时
        const timeout = new Promise((_, reject) => 
            setTimeout(() => reject(new Error('请求超时')), 5000)
        );
        
        const data = await Promise.race([
            fetchData(),
            timeout
        ]);
        
        return data;
    } catch (error) {
        if (error.message === '请求超时') {
            showMessage('请求超时，请重试');
        } else {
            showMessage('获取数据失败');
        }
        throw error;
    }
}

class WeatherApp {
    constructor(apiKey) {
        this.apiKey = apiKey;
        this.init();
    }
    
    async getWeather(city) {
        try {
            const url = `https://api.openweathermap.org/data/2.5/weather?q=\${city}&appid=\${this.apiKey}&units=metric&lang=zh_cn`;
            const response = await fetch(url);
            
            if (!response.ok) {
                throw new Error('城市未找到');
            }
            
            const data = await response.json();
            return {
                city: data.name,
                temperature: data.main.temp,
                description: data.weather[0].description,
                humidity: data.main.humidity,
                windSpeed: data.wind.speed
            };
        } catch (error) {
            console.error('获取天气失败:', error);
            throw error;
        }
    }
    
    displayWeather(weatherData) {
        const weatherDiv = document.getElementById('weather-display');
        weatherDiv.innerHTML = \`
            

                
\${weatherData.city}
                
温度: \${weatherData.temperature}°C
                
天气: \${weatherData.description}
                
湿度: \${weatherData.humidity}%
                
风速: \${weatherData.windSpeed} m/s
            
        \`;
    }
}