我将发布一种更声明性的同步Base64转换方式。虽然async fetch().blob()非常整洁，我非常喜欢这个解决方案，但它在Internet Explorer 11(可能还有Edge -我还没有测试过这个)上不起作用，即使是在polyfill上-看看我对Endless的帖子的评论，了解更多细节。

const blobPdfFromBase64String = base64String => {
   const byteArray = Uint8Array.from(
     atob(base64String)
       .split('')
       .map(char => char.charCodeAt(0))
   );
  return new Blob([byteArray], { type: 'application/pdf' });
};

奖金

如果你想打印它，你可以这样做:

const isIE11 = !!(window.navigator && window.navigator.msSaveOrOpenBlob); // Or however you want to check it
const printPDF = blob => {
   try {
     isIE11
       ? window.navigator.msSaveOrOpenBlob(blob, 'documents.pdf')
       : printJS(URL.createObjectURL(blob)); // http://printjs.crabbly.com/
   } catch (e) {
     throw PDFError;
   }
};

奖金x 2 -打开一个BLOB文件在新选项卡为Internet Explorer 11

如果你能够在服务器上对Base64字符串做一些预处理，你可以在一些URL下公开它，并使用printJS中的链接:)

对于所有像我一样喜欢复制粘贴的人来说，这里有一个可以在Chrome、Firefox和Edge上运行的现成下载功能:

window.saveFile = function (bytesBase64, mimeType, fileName) {
var fileUrl = "data:" + mimeType + ";base64," + bytesBase64;
fetch(fileUrl)
    .then(response => response.blob())
    .then(blob => {
        var link = window.document.createElement("a");
        link.href = window.URL.createObjectURL(blob, { type: mimeType });
        link.download = fileName;
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
    });
}

对于所有浏览器的支持，特别是在Android上，也许你可以添加这个:

try{
    blob = new Blob(byteArrays, {type : contentType});
}
catch(e){
    // TypeError old Google Chrome and Firefox
    window.BlobBuilder = window.BlobBuilder ||
                         window.WebKitBlobBuilder ||
                         window.MozBlobBuilder ||
                         window.MSBlobBuilder;
    if(e.name == 'TypeError' && window.BlobBuilder){
        var bb = new BlobBuilder();
        bb.append(byteArrays);
        blob = bb.getBlob(contentType);
    }
    else if(e.name == "InvalidStateError"){
        // InvalidStateError (tested on FF13 WinXP)
        blob = new Blob(byteArrays, {type : contentType});
    }
    else{
        // We're screwed, blob constructor unsupported entirely
    }
}

在浏览器中

Uint8Array.from(atob(YOUR_BASE64_DATA), (c) => c.charCodeAt(0))

与fetch比较

!(async () => {
  const start = performance.now();
  let i = 0;
  while (i++ < 1e3) {
    const dataUrl =
      "data:application/octet-stream;base64,H4sIAAAAAAAAA0vOzyvOz0nVy8lP10jISM3JyVdIr8osUFCpdkksSdXLyy/X0KxN0ORKHlU3qm5U3ai6UXWj6kauOgBVt1KRLwcAAA==";
    body = await (await fetch(dataUrl)).blob();
  }
  console.log(performance.now() - start); // 508.19999999925494ms
})();

!(async () => {
  const start = performance.now();
  let i = 0;
  while (i++ < 1e3) {
    const base64Data =
      "H4sIAAAAAAAAA0vOzyvOz0nVy8lP10jISM3JyVdIr8osUFCpdkksSdXLyy/X0KxN0ORKHlU3qm5U3ai6UXWj6kauOgBVt1KRLwcAAA==";
    body = Uint8Array.from(atob(base64Data), (c) => c.charCodeAt(0));
  }
  console.log(performance.now() - start); // 7.899999998509884ms
})();

根据您的数据大小，选择性能一种。

以下是我的TypeScript代码，可以很容易地转换成JavaScript，你可以使用

/**
 * Convert BASE64 to BLOB
 * @param base64Image Pass Base64 image data to convert into the BLOB
 */
private convertBase64ToBlob(base64Image: string) {
  // Split into two parts
  const parts = base64Image.split(';base64,');

  // Hold the content type
  const imageType = parts[0].split(':')[1];

  // Decode Base64 string
  const decodedData = window.atob(parts[1]);

  // Create UNIT8ARRAY of size same as row data length
  const uInt8Array = new Uint8Array(decodedData.length);

  // Insert all character code into uInt8Array
  for (let i = 0; i < decodedData.length; ++i) {
    uInt8Array[i] = decodedData.charCodeAt(i);
  }

  // Return BLOB image after conversion
  return new Blob([uInt8Array], { type: imageType });
}

这将被证明是一个很短的解决办法。

const byteArray = new Buffer(base64String.replace(/^[\w\d;:\/]+base64\,/g, ''), 'base64');

base64String是包含以64为基数的字符串。

byteArray是你需要的数组。

regex替换是可选的，只是用于处理dataurl字符串中的前缀。