ts

  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);
      },
    );


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

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

    response.type = matches[1];
    response.data = Buffer.from(matches[2], 'base64').toString('utf8');
    console.log(response);
    return response;
  }