Custom styles for BitBucket and Tampermonkey

BitBucketCustomStyles.js

// ==UserScript==
// @name         BitBucket Style Updates
// @namespace    http://mitmaro.ca
// @version      1.0.0
// @description  Converts the diff tab size on BB
// @author       Tim Oram
// @match        https://bitbucket.org/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    // Returns a function, that, as long as it continues to be invoked, will not
    // be triggered. The function will be called after it stops being called for
    // N milliseconds. If `immediate` is passed, trigger the function on the
    // leading edge, instead of the trailing.
    function debounce(func, wait, immediate) {
        var timeout;
        return function() {
            var context = this, args = arguments;
            var later = function() {
                timeout = null;
                if (!immediate) func.apply(context, args);
            };
            var callNow = immediate && !timeout;
            clearTimeout(timeout);
            timeout = setTimeout(later, wait);
            if (callNow) func.apply(context, args);
        };
    };
    var sheet = document.createElement('style');
    sheet.innerHTML = `
pre.source {
    tab-size: 4 !important;
}
#announcement {
    display: none;
}
`;
    document.body.appendChild(sheet);
    
    const pr = document.querySelector(`#pr-tab-content`);
		if (!pr) {
			return;
		}
    
    const handler = debounce((mutations, obs) => {
        console.log(new Date());
        const items = document.querySelectorAll('pre.source');
        const values = [].map.call(items, (el) => el.innerText);
        let i = 0;
        items.forEach((el) => el.innerHTML = values[++i]);
        console.log(new Date());
    }, 1000);
    
    const observer = new MutationObserver(handler);

    observer.observe(pr, {
        attributes: false,
        characterData: false,
        childList: true,
        subtree: true,
    });
})();