UploadFileToSharePoint.ts

public async uploadFileToSharePoint(documentLibrary: string, webUrl: string, fileName: string, fileB64: any): Promise <any> {
  try {
    const web = new Web(webUrl);
    documentLibrary = documentLibrary.replace(location.origin, "");
    console.log(documentLibrary);

    /*  const rs: FileAddResult = await web.getFolderByServerRelativeUrl(documentLibrary).files.add(fileName,fileB64,true); */
    const rs: FileAddResult = await web.getFolderByServerRelativeUrl(documentLibrary)
      .files.addChunked(
        fileName,
        fileB64,
        (data: ChunkedFileUploadProgressData) => {
          console.log(`File Upload chunked: ${(data.currentPointer / data.fileSize)}%`);
          return data.currentPointer / data.fileSize;
        },
        true
      );
    return rs;
  } catch (error) {
    console.log(error);
  }
}

https://raw.githubusercontent.com/SharePoint/sp-dev-fx-webparts/master/samples/react-mytasks/src/services/spservices.ts

https://github.com/SharePoint/sp-dev-fx-webparts/blob/3773b623e130375f701fa749101765d2eca997fa/samples/react-mytasks/src/Controls/UploadFile/UploadFile.tsx