ref: 9f1265fde4b9ef186148337c99f08601633b6056
dir: /_vendor/github.com/gohugoio/gohugoioTheme/assets/js/smoothscroll.js/
// query selector targets Hugo TOC
(function() {
'use strict';
// Feature Test
if ('querySelector' in document && 'addEventListener' in window && Array.prototype.forEach) {
// Function to animate the scroll
var smoothScroll = function(anchor, duration) {
// Calculate how far and how fast to scroll
var startLocation = window.pageYOffset;
var endLocation = anchor.offsetTop;
var distance = endLocation - startLocation;
var increments = distance / (duration / 16);
var stopAnimation;
// Scroll the page by an increment, and check if it's time to stop
var animateScroll = function() {
window.scrollBy(0, increments);
stopAnimation();
};
// If scrolling down
if (increments >= 0) {
// Stop animation when you reach the anchor OR the bottom of the page
stopAnimation = function() {
var travelled = window.pageYOffset;
if ((travelled >= (endLocation - increments)) || ((window.innerHeight + travelled) >= document.body.offsetHeight)) {
clearInterval(runAnimation);
}
};
}
// If scrolling up
else {
// Stop animation when you reach the anchor OR the top of the page
stopAnimation = function() {
var travelled = window.pageYOffset;
if (travelled <= (endLocation || 0)) {
clearInterval(runAnimation);
}
};
}
// Loop the animation function
var runAnimation = setInterval(animateScroll, 16);
};
// Define smooth scroll links
var scrollToggle = document.querySelectorAll('#TableOfContents ul li a');
// For each smooth scroll link
[].forEach.call(scrollToggle, function(toggle) {
// When the smooth scroll link is clicked
toggle.addEventListener('click', function(e) {
// Prevent the default link behavior
e.preventDefault();
// Get anchor link and calculate distance from the top
var dataID = toggle.getAttribute('href');
var dataTarget = document.querySelector(dataID);
var dataSpeed = toggle.getAttribute('data-speed');
// If the anchor exists
if (dataTarget) {
// Scroll to the anchor
smoothScroll(dataTarget, dataSpeed || 500);
}
}, false);
});
}
})();