js 手机 查看大图片尺寸

function getImageDimensions(url, callback) {
    const img = new Image();
    img.onload = function() {
        callback(null, { width: img.width, height: img.height });
    };
    img.onerror = function(error) {
        callback(error);
    };
    img.src = url;
}

// 使用示例
const imageUrl = 'https://example.com/large-image.jpg';
getImageDimensions(imageUrl, function(err, dimensions) {
    if (err) {
        console.error('加载图片失败:', err);
    } else {
        console.log('图片宽度:', dimensions.width);
        console.log('图片高度:', dimensions.height);
    }
});

async function getImageSize(url) {
    try {
        const response = await fetch(url, { method: 'HEAD' });
        if (!response.ok) throw new Error('网络响应不是OK');
        const contentLength = response.headers.get('Content-Length');
        // 注意：仅Content-Length无法获取尺寸，需要进一步处理
        // 实际上，获取尺寸仍需加载图片，故此方法主要用于检查图片是否存在及大小
        return null; // 需结合其他方法
    } catch (error) {
        console.error('获取图片信息失败:', error);
    }
}

// 结合Image对象获取尺寸
async function getImageDimensions(url) {
    return new Promise((resolve, reject) => {
        const img = new Image();
        img.onload = () => resolve({ width: img.width, height: img.height });
        img.onerror = reject;
        img.src = url;
    });
}

// 使用示例
const imageUrl = 'https://example.com/large-image.jpg';
getImageDimensions(imageUrl)
    .then(dimensions => {
        console.log('图片宽度:', dimensions.width);
        console.log('图片高度:', dimensions.height);
    })
    .catch(error => {
        console.error('加载图片失败:', error);
    });

img.onload = function() {
    const width = img.naturalWidth;
    const height = img.naturalHeight;
    console.log('原始宽度:', width);
    console.log('原始高度:', height);
};