web/_javascript/utils/smooth-scroll.js

96 lines
2.8 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() {
const $topbarTitle = $("#topbar-title");
const REM = 16; // in pixels
const ATTR_SCROLL_FOCUS = "scroll-focus";
$("a[href*='#']")
.not("[href='#']")
.not("[href='#0']")
.click(function(event) {
if (this.pathname.replace(/^\//, "") !==
location.pathname.replace(/^\//, "")) {
return;
}
if (location.hostname !== this.hostname) {
return;
}
const hash = decodeURI(this.hash);
let toFootnoteRef = RegExp(/^#fnref:/).test(hash);
let toFootnote = toFootnoteRef ? false : RegExp(/^#fn:/).test(hash);
let selector = hash.includes(":") ? hash.replace(/\:/g, "\\:") : hash;
let $target = $(selector);
let isMobileViews = $topbarTitle.is(":visible");
let isPortrait = $(window).width() < $(window).height();
if (typeof $target === "undefined") {
return;
}
event.preventDefault();
if (history.pushState) { /* add hash to URL */
history.pushState(null, null, hash);
}
let curOffset = $(window).scrollTop();
let destOffset = $target.offset().top -= REM / 2;
if (destOffset < curOffset) { // scroll up
ScrollHelper.hideTopbar();
ScrollHelper.addScrollUpTask();
if (isMobileViews && isPortrait) {
destOffset -= ScrollHelper.getTopbarHeight();
}
} else { // scroll down
if (isMobileViews && isPortrait) {
destOffset -= ScrollHelper.getTopbarHeight();
}
}
$("html").animate({
scrollTop: destOffset
}, 500, () => {
$target.focus();
/* clean up old scroll mark */
if ($(`[${ATTR_SCROLL_FOCUS}=true]`).length) {
$(`[${ATTR_SCROLL_FOCUS}=true]`).attr(ATTR_SCROLL_FOCUS, false);
}
/* Clean :target links */
if ($(":target").length) { /* element that visited by the URL with hash */
$(":target").attr(ATTR_SCROLL_FOCUS, false);
}
/* set scroll mark to footnotes */
if (toFootnote || toFootnoteRef) {
$target.attr(ATTR_SCROLL_FOCUS, true);
}
if ($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 */
}
if (ScrollHelper.hasScrollUpTask()) {
ScrollHelper.popScrollUpTask();
}
});
}); /* click() */
});