import { SecurityContext } from '@angular/core';
import { DomSanitizer } from '@angular/platform-browser';
private sanitizer: DomSanitizer;

downloadCSV() {

  let blob = new Blob([yourdata], { type: 'text/csv' });
  let urlPath = this.sanitizer.sanitize(SecurityContext.URL,
this.sanitizer.bypassSecurityTrustResourceUrl(window.URL.createObjectURL(blob)));
    
  let tempLink = document.createElement('a');
  tempLink.href = urlPath;
  tempLink.setAttribute('download', 'download.csv');
  tempLink.click();
}