js图片验证

function checkFileType(file) {
    const allowedTypes = ['image/jpeg', 'image/png', 'image/gif'];
    if (!allowedTypes.includes(file.type)) {
        alert('不支持的文件类型！');
        return false;
    }
    return true;
}

function checkFileSize(file, maxSize) {
    if (file.size > maxSize) {
        alert('文件大小超过限制！');
        return false;
    }
    return true;
}

function checkImageResolution(file, minWidth, minHeight) {
    return new Promise((resolve, reject) => {
        const img = new Image();
        img.onload = () => {
            if (img.width < minWidth || img.height < minHeight) {
                alert('图片分辨率过低！');
                reject(false);
            } else {
                resolve(true);
            }
        };
        img.onerror = () => reject(false);
        img.src = URL.createObjectURL(file);
    });
}