GitHub mutations observer library script
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/28721/187801/mutations.js
/* GitHub mutations observer library script v0.1.1
* Detect changes to various elements and trigger an event
* Copyright © 2017 Rob Garrison
* License: MIT
*/
/* jshint esnext:true, unused:true */
(() => {
"use strict";
// prefix for event & document body class name, e.g. "ghmo:container"
const prefix = "ghmo",
targets = {
// pjax container (covers general, repo & gists)
"[data-pjax-container]": {
count: 0,
name: "container"
},
// comment preview active
".js-preview-body": {
count: 0,
name: "preview"
},
// progressively loaded comments; "# items not shown"
// example: https://github.com/isaacs/github/issues/18
".js-discussion": {
count: 0,
name: "comments"
},
// progressively loaded content (diff files)
".js-diff-progressive-container, .js-diff-load-container": {
count: 0,
name: "diff"
}
},
list = Object.keys(targets),
container = document.querySelector("body");
let timer;
function fireEvents() {
list.forEach(selector => {
if (targets[selector].count > 0) {
// event => "ghmo:container", "ghmo:comments"
const event = new Event(prefix + ":" + targets[selector].name);
document.dispatchEvent(event);
}
targets[selector].count = 0;
});
}
// prevent script from installing more than once
if (!container.classList.contains(prefix + "-enabled")) {
container.classList.add(prefix + "-enabled");
new MutationObserver(mutations => {
mutations.forEach(mutation => {
clearTimeout(timer);
const target = mutation.target;
if (target) {
list.forEach(selector => {
if (target.matches(selector)) {
targets[selector].count++;
}
});
}
timer = setTimeout(() => {
fireEvents();
}, 100);
});
}).observe(container, {
childList: true,
subtree: true
});
}
})();