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blog_os/blog/static/js/edition-2/main.js
Philipp Oppermann 69917e234c Remember chosen theme in localStorage
This way, the selected theme is kept when changing pages, and for subsequent visits. To prevent flickering, we set the selected theme in a blocking script directly on load. To speed things up further, we now use a `data-theme` attribute instead of classes on the body tag, this way we don't need to wait until the body element is loaded.
2021-10-17 15:05:11 +02:00

86 lines
2.2 KiB
JavaScript

window.onload = function () {
let theme = localStorage.getItem("theme");
if (theme != null) {
set_theme(theme)
}
let container = document.querySelector('#toc-aside');
if (container != null) {
resize_toc(container);
toc_scroll_position(container);
window.onscroll = function () { toc_scroll_position(container) };
}
}
function resize_toc(container) {
let containerHeight = container.clientHeight;
let resize = function () {
if (containerHeight > document.documentElement.clientHeight - 100) {
container.classList.add('coarse');
} else {
container.classList.remove('coarse');
}
};
resize();
let resizeId;
window.onresize = function () {
clearTimeout(resizeId);
resizeId = setTimeout(resize, 300);
};
}
function toc_scroll_position(container) {
if (container.offsetParent === null) {
// skip computation if ToC is not visible
return;
}
// remove active class for all items
for (item of container.querySelectorAll("li")) {
item.classList.remove("active");
}
// look for active item
let site_offset = document.documentElement.scrollTop;
let current_toc_item = null;
for (item of container.querySelectorAll("li")) {
if (item.offsetParent === null) {
// skip items that are not visible
continue;
}
let anchor = item.firstElementChild.getAttribute("href");
let heading = document.querySelector(anchor);
if (heading.offsetTop <= (site_offset + document.documentElement.clientHeight / 3)) {
current_toc_item = item;
} else {
break;
}
}
// set active class for current ToC item
if (current_toc_item != null) {
current_toc_item.classList.add("active");
}
}
function toggle_lights() {
if (document.documentElement.getAttribute("data-theme") === "dark") {
set_theme("light")
} else {
set_theme("dark")
}
}
function set_theme(theme) {
let comment_form = document.querySelector("iframe.giscus-frame");
document.documentElement.setAttribute("data-theme", theme);
if (comment_form != null) {
comment_form.contentWindow.postMessage({
giscus: { setConfig: { theme: theme } }
}, "https://giscus.app")
}
localStorage.setItem("theme", theme);
}