$(document).ready(function(){
  // Add smooth scrolling to all links in navbar + footer link
  $(".navbar a, footer a[href='#back-to-top']").on('click', function(event) {

  // Prevent default anchor click behavior
  event.preventDefault();

  // Store hash
  var hash = this.hash;

  // Using jQuery's animate() method to add smooth page scroll
  // The optional number (900) specifies the number of milliseconds it takes to scroll to the specified area
  $('html, body').animate({
    scrollTop: $(hash).offset().top
  }, 900, function(){

    // Add hash (#) to URL when done scrolling (default click behavior)
    window.location.hash = hash;
    });
  });
})

Reference: Bootstrap Theme “Company”