jQuery scrolling fixen

$(() => {
$('a').on('click', (event) => {
  var $anchor = $(this);
  if($anchor.attr('href').substr(0, 9)==='#section_'){
    $('html, body').stop().animate({
      scrollTop: ($($anchor.attr('href')).offset().top - 150)
    }, 1250, 'easeInOutExpo');
   }
});
});