const b64toBlob = ( b64Data , contentType = '' , sliceSize = 512 ) : Blob => { const byteCharacters = atob ( b64Data ) ; const byteArrays = [ ] ; for ( let offset = 0 ; offset < byteCharacters . length ; offset += sliceSize ) { const slice = byteCharacters . slice ( offset , offset + sliceSize ) ; const byteNumbers = new Array ( slice . length ) ; for ( let i = 0 ; i < slice . length ; i ++ ) byteNumbers [ i ] = slice . charCodeAt ( i ) ; const byteArray = new Uint8Array ( byteNumbers ) ; byteArrays . push ( byteArray ) ; } const blob = new Blob ( byteArrays , { type : contentType } ) ; return blob ; } ; export default b64toBlob ;