web/_javascript/utils/smooth-scroll.js

81 lines
2.6 KiB
JavaScript

/*
Safari doesn't support CSS `scroll-behavior: smooth`,
so here is a compatible solution for all browser to smooth scrolling
See: <https://css-tricks.com/snippets/jquery/smooth-scrolling/>
Warning: It must be called after all `<a>` tags (e.g., the dynamic TOC) are ready.
*/
$(function() {
$("a[href*='#']")
.not("[href='#']")
.not("[href='#0']")
.click(function(event) {
if (this.pathname.replace(/^\//, "") === location.pathname.replace(/^\//, "")) {
if (location.hostname === this.hostname) {
const REM = 16; /* 16px */
const hash = decodeURI(this.hash);
let isFnRef = RegExp(/^#fnref:/).test(hash);
let isFn = isFnRef? false : RegExp(/^#fn:/).test(hash);
let selector = hash.includes(":") ? hash.replace(/\:/g, "\\:") : hash;
let target = $(selector);
if (target.length) {
event.preventDefault();
if (history.pushState) { /* add hash to URL */
history.pushState(null, null, hash);
}
let curOffset = $(this).offset().top;
let destOffset = target.offset().top;
const scrollUp = (destOffset < curOffset);
const topbarHeight = $("#topbar-wrapper").outerHeight();
if (scrollUp && isFnRef) {
/* Avoid the top-bar covering `fnref` when scrolling up
because `fnref` has no `%anchor`(see: module.scss) style. */
destOffset -= (topbarHeight + REM / 2);
}
$("html,body").animate({
scrollTop: destOffset
}, 800, () => {
const $target = $(target);
$target.focus();
const SCROLL_MARK = "scroll-focus";
/* clean up old scroll mark */
if ($(`[${SCROLL_MARK}=true]`).length) {
$(`[${SCROLL_MARK}=true]`).attr(SCROLL_MARK, false);
}
/* Clean :target links */
if ($(":target").length) { /* element that visited by the URL with hash */
$(":target").attr(SCROLL_MARK, false);
}
/* set scroll mark to footnotes */
if (isFn || isFnRef) {
$target.attr(SCROLL_MARK, true);
}
if ($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 */
}
});
}
}
}
}); /* click() */
});