Hi syed

thanks its work fine as you suggested thank you

here is my code

var attachLink='';

  var ga = new GlideRecord('sys_attachment');

  ga.addQuery('table_sys_id',this.tableId);

  ga.query();

  if (ga.hasNext()) {

  while (ga.next()) {

  attachLink = attachLink+ ga.file_name ;

  }

  }

  parsedBody = parsedBody.replace(/\$\{date\}/gi, date);

  parsedBody = parsedBody.replace(/\$\{letterid\}/gi, this.letterid);

  parsedBody = parsedBody.replace(/\$\{Attachments\}/gi,attachLink);