Ng5- Excel File download using POST request

Ng5- Excel File download using POST request:
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tempalte.html:
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<div (click)="download(modell)" style="margin:50px;border: solid #000">download Excel File in Angualr 5 using POST Request.</div>
  REf:https://stackoverflow.com/questions/49422518/angular-5-download-excel-file-with-post-request
 
component.ts:
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passModel = { /* posting object */ }
download(passModel) {
  //this.loadingOverlayFlag = true;
  this.graphService.DownloadData(passModel).subscribe(result=>{
    // console.log(result);
    this.downloadFile(result,'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'export.csv');
  })
}

downloadFile(blob: any, type: string, filename: string) {

  var binaryData = [];
  binaryData.push(blob);

  const url = window.URL.createObjectURL(new Blob(binaryData)); // <-- work with blob directly

   // create hidden dom element (so it works in all browsers)
   const a = document.createElement('a');
   a.setAttribute('style', 'display:none;');
   document.body.appendChild(a);

   // create file, attach to hidden element and open hidden element
   a.href = url;
   a.download = filename;
   a.click();
}

service.ts:
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DownloadData(model):Observable<any>{
    return new Observable(obs => {
      var oReq = new XMLHttpRequest();
      oReq.open("POST", 'http://localhost:8080/api/downlaod/excel', true);
      oReq.setRequestHeader("content-type", "application/json");
      oReq.responseType = "arraybuffer";
 
      oReq.onload = function (oEvent) {
        var arrayBuffer = oReq.response;
        var byteArray = new Uint8Array(arrayBuffer);
        obs.next(byteArray);
      };
 
      const body = JSON.stringify(model);
      oReq.send(body);
    });
  }