Show total changed lines of code for all files combined in a PR (new view) on Bitbucket. This is a TamperMonkey script.

bitbucket-pr-totals.js

// ==UserScript==
// @name         Bitbucket totals in PR
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Show total changed lines of code
// @author       You
// @match        https://bitbucket.org/*/*/pull-requests/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    window.addEventListener('load', function() {
        setTimeout(() => {
            const total = (a, c) => a + c;
            const innerToInt = ele => parseInt(ele.innerHTML);
            const containsNumber = ele => ele.innerHTML.match(/^[+-].\d*$/);
            const allSpanTags = Array(...document.getElementsByTagName('span'));
            const totalForAllNumbers = allSpanTags.filter(containsNumber).map(innerToInt).reduce(total, 0);

            const colorInt = (int) => parseInt(int) < 0 ? `<font color=darkred>${int}</font>` : `<font color=green>${int}</font>`;
            // set the total change number next to header text for that column
            document
                .querySelector('#PullRequestWelcomeTourTarget-Files > section > button > span:nth-of-type(2) > span')
                .insertAdjacentHTML('beforeend', ` <small>affected lines: <b>${colorInt(totalForAllNumbers)}</b></small>`);
        }, 500);
    }, false);
})();

Result:

(this particular PR removed more lines of code than it added)