github.com/lyeb/hugo@v0.47.1/docs/themes/gohugoioTheme/src/js/smoothscroll.js (about)

     1  // query selector targets Hugo TOC 
     2  (function() {
     3  
     4    'use strict';
     5  
     6    // Feature Test
     7    if ('querySelector' in document && 'addEventListener' in window && Array.prototype.forEach) {
     8  
     9      // Function to animate the scroll
    10      var smoothScroll = function(anchor, duration) {
    11  
    12        // Calculate how far and how fast to scroll
    13        var startLocation = window.pageYOffset;
    14        var endLocation = anchor.offsetTop;
    15        var distance = endLocation - startLocation;
    16        var increments = distance / (duration / 16);
    17        var stopAnimation;
    18  
    19        // Scroll the page by an increment, and check if it's time to stop
    20        var animateScroll = function() {
    21          window.scrollBy(0, increments);
    22          stopAnimation();
    23        };
    24  
    25        // If scrolling down
    26        if (increments >= 0) {
    27          // Stop animation when you reach the anchor OR the bottom of the page
    28          stopAnimation = function() {
    29            var travelled = window.pageYOffset;
    30            if ((travelled >= (endLocation - increments)) || ((window.innerHeight + travelled) >= document.body.offsetHeight)) {
    31              clearInterval(runAnimation);
    32            }
    33          };
    34        }
    35        // If scrolling up
    36        else {
    37          // Stop animation when you reach the anchor OR the top of the page
    38          stopAnimation = function() {
    39            var travelled = window.pageYOffset;
    40            if (travelled <= (endLocation || 0)) {
    41              clearInterval(runAnimation);
    42            }
    43          };
    44        }
    45  
    46        // Loop the animation function
    47        var runAnimation = setInterval(animateScroll, 16);
    48  
    49      };
    50  
    51      // Define smooth scroll links
    52      var scrollToggle = document.querySelectorAll('#TableOfContents ul li a');
    53  
    54      // For each smooth scroll link
    55      [].forEach.call(scrollToggle, function(toggle) {
    56  
    57        // When the smooth scroll link is clicked
    58        toggle.addEventListener('click', function(e) {
    59  
    60          // Prevent the default link behavior
    61          e.preventDefault();
    62  
    63          // Get anchor link and calculate distance from the top
    64          var dataID = toggle.getAttribute('href');
    65          var dataTarget = document.querySelector(dataID);
    66          var dataSpeed = toggle.getAttribute('data-speed');
    67  
    68          // If the anchor exists
    69          if (dataTarget) {
    70            // Scroll to the anchor
    71            smoothScroll(dataTarget, dataSpeed || 500);
    72          }
    73  
    74        }, false);
    75  
    76      });
    77  
    78    }
    79  
    80  })();