function loadScript(src: string, async:boolean, callback: (isLoaded:boolean) => void) {
  const firstElement = document.getElementsByTagName('head')[0] || document.documentElement,
  scriptElement = document.createElement('script');
  scriptElement.type = 'text/javascript';
  scriptElement.src = src;
  scriptElement.async = async;
  scriptElement.addEventListener('load', function() {
    if(callback && typeof callback === 'function') {
      callback(true);
    }
  }, false);
  scriptElement.addEventListener('error', function() {
    firstElement.removeChild(scriptElement);
    if(callback && typeof callback === 'function') {
      callback(false);
    }
  }, false);
  firstElement.insertBefore(scriptElement, firstElement.firstChild);
}
export {
  loadScript
}