您必须从它中剥离url meta信息，即data:image/jpeg部分。（重复@CBroe所说的）下面是一个小函数，用于从输入字符串返回正确的信息。

var data = 'data:image/jpeg;base64,iVBORw0KGgoAAAANSUhEUgAAA..kJggg==';

function decodeBase64Image(dataString) {
  var matches = dataString.match(/^data:([A-Za-z-+\/]+);base64,(.+)$/),
    response = {};

  if (matches.length !== 3) {
    return new Error('Invalid input string');
  }

  response.type = matches[1];
  response.data = new Buffer(matches[2], 'base64');

  return response;
}

var imageBuffer = decodeBase64Image(data);
console.log(imageBuffer);
// { type: 'image/jpeg',
//   data: <Buffer 89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 00 00 00 b4 00 00 00 2b 08 06 00 00 00 d1 fd a2 a4 00 00 00 04 67 41 4d 41 00 00 af c8 37 05 8a e9 00 00 ...> }

然后可以使用上面的方法保存缓冲区。

fs.writeFile('test.jpg', imageBuffer.data, function(err) { ... });

另一种方法是在剥离 meta信息之后使用带有编码选项base64的fs.writeFile。

var image = 'data:image/jpeg;base64,iVBORw0KGgoAAAANSUhEUgAAA..kJggg==';

var data = image.replace(/^data:image\/\w+;base64,/, '');

fs.writeFile(fileName, data, {encoding: 'base64'}, function(err){
  //Finished
});

在这里你可以用我做的小改动

var imgData = req.body.image;// coming from client request
  var base64Data = imgData.split(",")[1];// split with `,`

   require("fs").writeFile(Date.now()+"filename.jpeg", base64Data, 'base64', 
    function(err, data) {
       if (err) {
      console.log('err', err);
         }
        console.log(data,"data");

最后你的文件看起来像1572341624757filename.jpeg

试试这个简单的方法

var imgData = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAA..kJggg==';
var base64Data = imgData.replace(/^data:image\/png;base64,/, "");

require("fs").writeFile("out.png", base64Data, 'base64', 
function(err, data) {
if (err) {
    console.log('err', err);
}
console.log('success');

});

请关注此处1）data:image/png;base存在png 2）此处也存在replace(/^data:image\/png;png且名称必须保存为3）writeFile("out.pngpng

var crypto = require('crypto');
var seed = crypto.randomBytes(20);
var uniqueSHA1String = crypto.createHash('sha1').update(seed).digest('hex');
var imageTypeRegularExpression = /\/(.*?)$/;

var imageBuffer = this.decodeBase64Image(createSlideshowDto.base64);
var imageTypeDetected = imageBuffer.type.match(imageTypeRegularExpression);

var data = createSlideshowDto.base64.replace(
  /^data:image\/\w+;base64,/,
  '',
);
console.log(data);
fs.writeFile(
  `./files/base64-${uniqueSHA1String}.${imageTypeDetected[1]}}`,
  data,
  { encoding: 'base64' },
  function (err) {
    //Finished

    console.log(err);
  },
);