js base64转化为文件

function base64ToFile(base64String, fileName, mimeType) {
    // 去除 Base64 字符串中的前缀（如果有）
    const base64Data = base64String.split(';base64,').pop();
    
    // 将 Base64 字符串解码为 ArrayBuffer
    const byteCharacters = atob(base64Data);
    const byteNumbers = new Array(byteCharacters.length);
    for (let i = 0; i < byteCharacters.length; i++) {
        byteNumbers[i] = byteCharacters.charCodeAt(i);
    }
    const byteArray = new Uint8Array(byteNumbers);
    
    // 创建 Blob 对象
    const blob = new Blob([byteArray], { type: mimeType });
    
    // 创建下载链接并触发下载
    const link = document.createElement('a');
    link.href = URL.createObjectURL(blob);
    link.download = fileName;
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
}

// 使用示例
const base64Image = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA...";
base64ToFile(base64Image, 'image.png', 'image/png');