Convert base64 into blob

b64ToBlob.js

b64toBlob(b64Data, contentType, sliceSize = 512) {
        contentType = contentType || '';
        sliceSize = sliceSize || 512;

        let byteCharacters = atob(b64Data);
        let byteArrays = [];

        for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
            let slice = byteCharacters.slice(offset, offset + sliceSize);

            let byteNumbers = new Array(slice.length);
            for (let i = 0; i < slice.length; i++) {
                byteNumbers[i] = slice.charCodeAt(i);
            }

            let byteArray = new Uint8Array(byteNumbers);

            byteArrays.push(byteArray);
        }

      let blob = new Blob(byteArrays, {type: contentType});
      return blob;
  }