var scroll = new SmoothScroll('a[href*="#"]'); code example

Example 1: javascript smooth scroll to anchor element

//add smooth scrolling when clicking any anchor link
document.querySelectorAll('a[href^="#"]').forEach(anchor => {
    anchor.addEventListener('click', function (e) {
        e.preventDefault();
        document.querySelector(this.getAttribute('href')).scrollIntoView({
            behavior: 'smooth'
        });
    });
});
//<a href="#someOtherElementID"> Go to Other Element Smoothly </a>

Example 2: smooth scroll

// 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' 
});