google_sheets_check_url_repsonse_code.js

function HTTPResponse( uri ) {
  var response_code ;
  var options = {
    'validateHttpsCertificates' : false
  };
  try {
    response_code = UrlFetchApp .fetch( uri, options ) .getResponseCode() .toString() ;
  }
  catch( error ) {
    response_code = error .toString() //.match( / returned code (\d\d\d)\./ )[1] ;
  }
  finally {
    return response_code ;
  }
}