smooth scrolll to id js

                                    // Select all links with hashes
$('a[href*="#"]')
  // Remove links that don't actually link to anything
  .not('[href="#"]')
  .not('[href="#0"]')
  .click(function(event) {
    // On-page links
    if (
      location.pathname.replace(/^\//, '') == this.pathname.replace(/^\//, '') 
      && 
      location.hostname == this.hostname
    ) {
      // Figure out element to scroll to
      var target = $(this.hash);
      target = target.length ? target : $('[name=' + this.hash.slice(1) + ']');
      // Does a scroll target exist?
      if (target.length) {
        // Only prevent default if animation is actually gonna happen
        event.preventDefault();
        $('html, body').animate({
          scrollTop: target.offset().top
        }, 1000, function() {
          // Callback after animation
          // Must change focus!
          var $target = $(target);
          $target.focus();
          if ($target.is(":focus")) { // Checking if the target was focused
            return false;
          } else {
            $target.attr('tabindex','-1'); // Adding tabindex for elements not focusable
            $target.focus(); // Set focus again
          };
        });
      }
    }
  });

                                    html {
  scroll-behavior: smooth;
}

/* No support in IE, or Safari
You can use this JS polyfill for those */
http://iamdustan.com/smoothscroll/

                                    // handle links with @href started with '#' only
$(document).on('click', 'a[href^="#"]', function(e) {
    // target element id
    var id = $(this).attr('href');

    // target element
    var $id = $(id);
    if ($id.length === 0) {
        return;
    }

    // prevent standard hash navigation (avoid blinking in IE)
    e.preventDefault();

    // top position relative to the document
    var pos = $id.offset().top;

    // animated top scrolling
    $('body, html').animate({scrollTop: pos});
});

                                    // Scroll to specific values
// scrollTo is the same
window.scroll({
  top: 2500, 
  left: 0, 
  behavior: 'smooth'
});

// Scroll certain amounts from current position 
window.scrollBy({ 
  top: 100, // could be negative value
  left: 0, 
  behavior: 'smooth' 
});

// Scroll to a certain element
document.querySelector('.hello').scrollIntoView({ 
  behavior: 'smooth' 
});