github.com.js

var isGitHub = $("meta[property='og:site_name']").attr('content') === 'GitHub';
var useLocalStorage = true;
var lsNamespace = 'ppr'; // Prepend to entries in localStorage for some namespacing to make deletion easier.
var pullRequestNumber;
var commitHash;
var repositoryName;
var repositoryAuthor;
var autoCollapseExpressions;

function htmlShouldBeInjected() {
  return $('a[href$="/files"].tabnav-tab.selected').length > 0 && $('.pretty-pull-requests-inserted').length <= 0;
}

function injectHtml() {
  $('<span class="pretty-pull-requests collapse-lines">' +
        '<label><input type="checkbox" class="js-collapse-additions" checked="yes">+</label>' +
        '<label><input type="checkbox" class="js-collapse-deletions" checked="yes">-</label>' +
    '</span>').insertAfter('.actions, .file-actions');

  $('<span class="pretty-pull-requests hide-whitespace">' +
        '<label>Hide whitespace changes <input type="checkbox" class="js-hide-whitespace"></label>' +
    '</span>').insertAfter('.diffbar-item.diffstat');
  $('.js-hide-whitespace').prop('checked', isWhitespaceHidden());

  $('<div class="pretty-pull-requests bottom-collapse">Click to Collapse</div>').insertAfter('.data.highlight.blob-wrapper');
  $('<div class="pretty-pull-requests-inserted" style="display: none"></div>').appendTo('body');
}

function collapseAdditions() {
    if (isGitHub) {
        $(this).closest('[id^=diff-]').find('.blob-code-addition').parent('tr').slideToggle();
    } else {
        $(this).closest('[id^=diff-]').find('.gi').slideToggle();
    }
}

function collapseDeletions() {
    if (isGitHub) {
        $(this).closest('[id^=diff-]').find('.blob-code-deletion').parent('tr').slideToggle();
    } else {
        $(this).closest('[id^=diff-]').find('.gd').slideToggle();
    }
}

// Whitespace is hidden if query parameter w=1 is set
function isWhitespaceHidden() {
    var regex = new RegExp("[?;&]w(=([^&;#]*)|&|;|#|$)"),
        results = regex.exec(window.location.search);
    return results && results[2] && results[2] === '1';
}

function toggleWhitespace() {
    window.location.search = setQueryParam(window.location.search, 'w', (isWhitespaceHidden() ? '0' : '1'));
}

var setQueryParam = function(search, key, val){
    var newParam = key + '=' + val;
    if (search.length === 0) {
        return '?' + newParam;
    }
    var searchNew = search.replace(new RegExp('([?;&])' + key + '[^;&]*'), '$1' + newParam);
    if (searchNew === search) {
        searchNew += '&' + newParam;
    }
    return searchNew;
};

function getDiffSpans(path) {
    return $('.file-info .link-gray-dark').filter(function () {
        return this.title.trim().match(path);
    });
}

function getIds(path) {
    var $spans = getDiffSpans(path).closest('[id^=diff-]');
    var $as = $spans.prev('a[name^=diff-]');
    var $ids = $as.map(function(index, a) {
        return $(a).attr('name');
    });

    return $ids;
}

function getId(path) {
    var $span = $('a[title="' + path + '"]').closest('[id^=diff-]');
    var $a = $span.prev('a[name^=diff-]');
    var id = $a.attr('name');

    return id;
}

function uniquify(diffId) {
  var diffViewId = pullRequestNumber || commitHash;

  return lsNamespace + '|' + repositoryAuthor + '|' + repositoryName + '|' + diffViewId + '|' + diffId;
}

function collectUniquePageInfo() {
  repositoryAuthor = $('[itemprop="author"]').find('a').text();
  repositoryName = $('strong[itemprop="name"]').find('a').text();
  pullRequestNumber = $('.gh-header-number').text();
  commitHash = $('.sha.user-select-contain').text();
}

function toggleDiff(id, duration, display) {
    var $a = $('a[name^=' + id + ']');
    duration = !isNaN(duration) ? duration : 200;

    if ($.inArray(display, ['expand', 'collapse', 'toggle']) < 0) {
        if (!useLocalStorage) {
            display = 'toggle';
        } else {
            display = (localStorage.getItem(uniquify(id)) === 'collapse') ? 'expand' : 'collapse';
        }
    }

    if ($a) {
        var $span = $a.next('div[id^=diff-]');
        var $data = $span.children('.js-file-content');
        switch (display) {
            case 'toggle':
                $data.toggle(duration);
                return true;
            case 'expand':
                $data.slideDown(duration);
                return useLocalStorage ? localStorage.removeItem(uniquify(id)) : true;
            default:
                $data.slideUp(duration);
                return useLocalStorage ? localStorage.setItem(uniquify(id), display) : true;
        }
    }
    return false;
}

function toggleDiffs(path, display) {
    var $ids = getIds(path);

    $ids.each(function(index, id) {
        toggleDiff(id, 200, display);
    });
}

function moveToNextTab($pullRequestTabs, selectedTabIndex) {
    selectedTabIndex += 1;
    if (selectedTabIndex >= $pullRequestTabs.length) {
        selectedTabIndex = 0;
    }
    $pullRequestTabs[selectedTabIndex].click();
}

function moveToPreviousTab($pullRequestTabs, selectedTabIndex) {
    selectedTabIndex -= 1;
    if (selectedTabIndex < 0) {
        selectedTabIndex = $pullRequestTabs.length - 1;
    }
    $pullRequestTabs[selectedTabIndex].click();
}

function initDiffs() {
    if (useLocalStorage) {
        $('a[name^=diff-]').each(function(index, item) {
            var id = $(item).attr('name');

            if (localStorage.getItem(uniquify(id)) === 'collapse') {
                toggleDiff(id, 0, 'collapse');
            }
        });
    }
    autoCollapse();
}

function clickTitle() {
    var path = $(this).attr('title');
    var id = getId(path);

    return toggleDiff(id);
}

function clickCollapse() {
    var $span = $(this).closest('.js-file-content').prev('.file-header');
    var path = $span.attr('data-path');
    var id = getId(path);

    return toggleDiff(id, '200', 'collapse');
}

function autoCollapse() {
    autoCollapseExpressions.forEach(item => {
        toggleDiffs(item, 'collapse');
    });
}

chrome.storage.sync.get({url: '', saveCollapsedDiffs: true, tabSwitchingEnabled: false, autoCollapseExpressions: []}, function(items) {
    if (items.url == window.location.origin ||
        "https://github.com" === window.location.origin) {

        autoCollapseExpressions = items.autoCollapseExpressions;

        var injectHtmlIfNecessary = function () {
            if (htmlShouldBeInjected()) {
                collectUniquePageInfo();
                injectHtml();
                initDiffs();
                $body.on('click', '.file-info .link-gray-dark', clickTitle);
                $body.on('click', '.bottom-collapse', clickCollapse);
                $body.on('click', '.js-collapse-additions', collapseAdditions);
                $body.on('click', '.js-collapse-deletions', collapseDeletions);
                $body.on('click', '.js-hide-whitespace', toggleWhitespace);
            }
            setTimeout(injectHtmlIfNecessary, 1000);
        };
        var $body = $('body');
        useLocalStorage = items.saveCollapsedDiffs;

        injectHtmlIfNecessary();

        if (items.tabSwitchingEnabled) {
          $body.on('keydown', function (e) {
              if (e.keyCode !== 192 || e.target.nodeName === 'TEXTAREA') {
                  return;
              }

              var $pullRequestTabs = $('nav.tabnav-tabs a.tabnav-tab');
              var $selectedTab     = $('nav.tabnav-tabs a.tabnav-tab.selected');
              var selectedTabIndex = $pullRequestTabs.index( $selectedTab );

              if (e.shiftKey) {
                  // Making this work like it would in other apps, where the shift
                  // key makes the cmd+tilde go backwards through the list.
                  moveToPreviousTab($pullRequestTabs, selectedTabIndex);
              } else {
                  moveToNextTab($pullRequestTabs, selectedTabIndex);
              }
          });
        }

        // Actions per changed file
        chrome.runtime.onConnect.addListener(function (port) {
            console.assert(port.name == "pullrequest");

            port.onMessage.addListener(function (msg) {
                if (msg.collapse !== undefined) {
                    toggleDiffs(msg.collapse, 'collapse');
                }
                if (msg.expand !== undefined) {
                    toggleDiffs(msg.expand, 'expand');
                }
                if (msg.goto !== undefined) {
                    getDiffSpans(msg.goto)[0].scrollIntoViewIfNeeded();
                }
            });
        });

        // Create the tree with the changed files after pressing the octocat button
        chrome.runtime.onMessage.addListener(function (request, sender, sendResponse) {
            if (request.getPaths) {
                var paths = $.map($('.file-info .link-gray-dark'), function (item) {
                    return $.trim(item.title);
                });
                if (paths.length > 0) {
                    sendResponse({paths: paths});
                }
            }
        });
    }
});