Move callback to the () => {} syntax.

Fix lint

Fix main.js

Restore anonymous functions

Fix

Fix more

6 files changed, 109 insertions, 112 deletions

diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index f20061c65dd..1dfd9c762c4 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -1,6 +1,7 @@
 /* eslint-env es6 */
 /* eslint no-var: "error" */
 /* eslint prefer-const: "error" */
+/* eslint prefer-arrow-callback: "error" */
 // Local js definitions:
 /* global addClass, getSettingValue, hasClass, searchState */
 /* global onEach, onEachLazy, removeClass */
@@ -152,7 +153,7 @@ function hideThemeButtonState() {
     themePicker.style.borderBottomLeftRadius = "3px";
 }
 
-window.hideSettings = function() {
+window.hideSettings = () => {
     // Does nothing by default.
 };
 
@@ -190,10 +191,10 @@ window.hideSettings = function() {
 
     themePicker.onclick = switchThemeButtonState;
     themePicker.onblur = handleThemeButtonsBlur;
-    availableThemes.forEach(function(item) {
+    availableThemes.forEach(item => {
         const but = document.createElement("button");
         but.textContent = item;
-        but.onclick = function() {
+        but.onclick = () => {
             switchTheme(window.currentTheme, window.mainTheme, item, true);
             useSystemTheme(false);
         };
@@ -300,7 +301,7 @@ function loadCss(cssFileName) {
     }
 
 
-    getSettingsButton().onclick = function(event) {
+    getSettingsButton().onclick = event => {
         event.preventDefault();
         loadScript(window.settingsJS);
     };
@@ -308,7 +309,7 @@ function loadCss(cssFileName) {
     window.searchState = {
         loadingText: "Loading search results...",
         input: document.getElementsByClassName("search-input")[0],
-        outputElement: function() {
+        outputElement: () => {
             let el = document.getElementById("search");
             if (!el) {
                 el = document.createElement("section");
@@ -328,24 +329,22 @@ function loadCss(cssFileName) {
         currentTab: 0,
         // tab and back preserves the element that was focused.
         focusedByTab: [null, null, null],
-        clearInputTimeout: function() {
+        clearInputTimeout: () => {
             if (searchState.timeout !== null) {
                 clearTimeout(searchState.timeout);
                 searchState.timeout = null;
             }
         },
-        isDisplayed: function() {
-            return searchState.outputElement().parentElement.id === ALTERNATIVE_DISPLAY_ID;
-        },
+        isDisplayed: () => searchState.outputElement().parentElement.id === ALTERNATIVE_DISPLAY_ID,
         // Sets the focus on the search bar at the top of the page
-        focus: function() {
+        focus: () => {
             searchState.input.focus();
         },
         // Removes the focus from the search bar.
-        defocus: function() {
+        defocus: () => {
             searchState.input.blur();
         },
-        showResults: function(search) {
+        showResults: search => {
             if (search === null || typeof search === 'undefined') {
                 search = searchState.outputElement();
             }
@@ -353,7 +352,7 @@ function loadCss(cssFileName) {
             searchState.mouseMovedAfterSearch = false;
             document.title = searchState.title;
         },
-        hideResults: function() {
+        hideResults: () => {
             switchDisplayedElement(null);
             document.title = searchState.titleBeforeSearch;
             // We also remove the query parameter from the URL.
@@ -362,17 +361,17 @@ function loadCss(cssFileName) {
                     getNakedUrl() + window.location.hash);
             }
         },
-        getQueryStringParams: function() {
+        getQueryStringParams: () => {
             const params = {};
             window.location.search.substring(1).split("&").
-                map(function(s) {
+                map(s => {
                     const pair = s.split("=");
                     params[decodeURIComponent(pair[0])] =
                         typeof pair[1] === "undefined" ? null : decodeURIComponent(pair[1]);
                 });
             return params;
         },
-        setup: function() {
+        setup: () => {
             const search_input = searchState.input;
             if (!searchState.input) {
                 return;
@@ -386,13 +385,13 @@ function loadCss(cssFileName) {
                 }
             }
 
-            search_input.addEventListener("focus", function() {
+            search_input.addEventListener("focus", () => {
                 search_input.origPlaceholder = search_input.placeholder;
                 search_input.placeholder = "Type your search here.";
                 loadSearch();
             });
 
-            if (search_input.value != '') {
+            if (search_input.value !== '') {
                 loadSearch();
             }
 
@@ -620,7 +619,7 @@ function loadCss(cssFileName) {
     document.addEventListener("keydown", handleShortcut);
 
     // delayed sidebar rendering.
-    window.initSidebarItems = function(items) {
+    window.initSidebarItems = items => {
         const sidebar = document.getElementsByClassName("sidebar-elems")[0];
         let others;
         const current = window.sidebarCurrent;
@@ -731,7 +730,7 @@ function loadCss(cssFileName) {
         }
     };
 
-    window.register_implementors = function(imp) {
+    window.register_implementors = imp => {
         const implementors = document.getElementById("implementors-list");
         const synthetic_implementors = document.getElementById("synthetic-implementors-list");
         const inlined_types = new Set();
@@ -742,12 +741,12 @@ function loadCss(cssFileName) {
             //
             // By the way, this is only used by and useful for traits implemented automatically
             // (like "Send" and "Sync").
-            onEachLazy(synthetic_implementors.getElementsByClassName("impl"), function(el) {
+            onEachLazy(synthetic_implementors.getElementsByClassName("impl"), el => {
                 const aliases = el.getAttribute("data-aliases");
                 if (!aliases) {
                     return;
                 }
-                aliases.split(",").forEach(function(alias) {
+                aliases.split(",").forEach(alias => {
                     inlined_types.add(alias);
                 });
             });
@@ -781,7 +780,7 @@ function loadCss(cssFileName) {
                 addClass(code, "code-header");
                 addClass(code, "in-band");
 
-                onEachLazy(code.getElementsByTagName("a"), function(elem) {
+                onEachLazy(code.getElementsByTagName("a"), elem => {
                     const href = elem.getAttribute("href");
 
                     if (href && href.indexOf("http") !== 0) {
@@ -826,7 +825,7 @@ function loadCss(cssFileName) {
         let sectionIsCollapsed = false;
         if (hasClass(innerToggle, "will-expand")) {
             removeClass(innerToggle, "will-expand");
-            onEachLazy(document.getElementsByClassName("rustdoc-toggle"), function(e) {
+            onEachLazy(document.getElementsByClassName("rustdoc-toggle"), e => {
                 if (!hasClass(e, "type-contents-toggle")) {
                     e.open = true;
                 }
@@ -834,7 +833,7 @@ function loadCss(cssFileName) {
             innerToggle.title = "collapse all docs";
         } else {
             addClass(innerToggle, "will-expand");
-            onEachLazy(document.getElementsByClassName("rustdoc-toggle"), function(e) {
+            onEachLazy(document.getElementsByClassName("rustdoc-toggle"), e => {
                 if (e.parentNode.id !== "implementations-list" ||
                     (!hasClass(e, "implementors-toggle") &&
                      !hasClass(e, "type-contents-toggle")))
@@ -861,7 +860,7 @@ function loadCss(cssFileName) {
         function setImplementorsTogglesOpen(id, open) {
             const list = document.getElementById(id);
             if (list !== null) {
-                onEachLazy(list.getElementsByClassName("implementors-toggle"), function(e) {
+                onEachLazy(list.getElementsByClassName("implementors-toggle"), e => {
                     e.open = open;
                 });
             }
@@ -872,7 +871,7 @@ function loadCss(cssFileName) {
             setImplementorsTogglesOpen("blanket-implementations-list", false);
         }
 
-        onEachLazy(document.getElementsByClassName("rustdoc-toggle"), function (e) {
+        onEachLazy(document.getElementsByClassName("rustdoc-toggle"), e => {
             if (!hideLargeItemContents && hasClass(e, "type-contents-toggle")) {
                 e.open = true;
             }
@@ -890,9 +889,9 @@ function loadCss(cssFileName) {
 
     (function() {
         // To avoid checking on "rustdoc-line-numbers" value on every loop...
-        let lineNumbersFunc = function() {};
+        let lineNumbersFunc = () => {};
         if (getSettingValue("line-numbers") === "true") {
-            lineNumbersFunc = function(x) {
+            lineNumbersFunc = x => {
                 const count = x.textContent.split("\n").length;
                 const elems = [];
                 for (let i = 0; i < count; ++i) {
@@ -904,7 +903,7 @@ function loadCss(cssFileName) {
                 x.parentNode.insertBefore(node, x);
             };
         }
-        onEachLazy(document.getElementsByClassName("rust-example-rendered"), function(e) {
+        onEachLazy(document.getElementsByClassName("rust-example-rendered"), e => {
             if (hasClass(e, "compile_fail")) {
                 e.addEventListener("mouseover", function() {
                     this.parentElement.previousElementSibling.childNodes[0].style.color = "#f00";
@@ -935,34 +934,34 @@ function loadCss(cssFileName) {
             elem.addEventListener("click", f);
         }
     }
-    handleClick("help-button", function(ev) {
+    handleClick("help-button", ev => {
         displayHelp(true, ev);
     });
-    handleClick(MAIN_ID, function() {
+    handleClick(MAIN_ID, () => {
         hideSidebar();
     });
 
-    onEachLazy(document.getElementsByTagName("a"), function(el) {
+    onEachLazy(document.getElementsByTagName("a"), el => {
         // For clicks on internal links (<A> tags with a hash property), we expand the section we're
         // jumping to *before* jumping there. We can't do this in onHashChange, because it changes
         // the height of the document so we wind up scrolled to the wrong place.
         if (el.hash) {
-            el.addEventListener("click", function() {
+            el.addEventListener("click", () => {
                 expandSection(el.hash.slice(1));
                 hideSidebar();
             });
         }
     });
 
-    onEachLazy(document.querySelectorAll(".rustdoc-toggle > summary:not(.hideme)"), function(el) {
-        el.addEventListener("click", function(e) {
-            if (e.target.tagName != "SUMMARY" && e.target.tagName != "A") {
+    onEachLazy(document.querySelectorAll(".rustdoc-toggle > summary:not(.hideme)"), el => {
+        el.addEventListener("click", e => {
+            if (e.target.tagName !== "SUMMARY" && e.target.tagName !== "A") {
                 e.preventDefault();
             }
         });
     });
 
-    onEachLazy(document.getElementsByClassName("notable-traits"), function(e) {
+    onEachLazy(document.getElementsByClassName("notable-traits"), e => {
         e.onclick = function() {
             this.getElementsByClassName('notable-traits-tooltiptext')[0]
                 .classList.toggle("force-tooltip");
@@ -971,7 +970,7 @@ function loadCss(cssFileName) {
 
     const sidebar_menu_toggle = document.getElementsByClassName("sidebar-menu-toggle")[0];
     if (sidebar_menu_toggle) {
-        sidebar_menu_toggle.addEventListener("click", function() {
+        sidebar_menu_toggle.addEventListener("click", () => {
             const sidebar = document.getElementsByClassName("sidebar")[0];
             if (!hasClass(sidebar, "shown")) {
                 addClass(sidebar, "shown");
@@ -981,12 +980,12 @@ function loadCss(cssFileName) {
         });
     }
 
-    let buildHelperPopup = function() {
+    let buildHelperPopup = () => {
         const popup = document.createElement("aside");
         addClass(popup, "hidden");
         popup.id = "help";
 
-        popup.addEventListener("click", function(ev) {
+        popup.addEventListener("click", ev => {
             if (ev.target === popup) {
                 // Clicked the blurred zone outside the help popup; dismiss help.
                 displayHelp(false, ev);
@@ -1009,14 +1008,10 @@ function loadCss(cssFileName) {
             ["&#9166;", "Go to active search result"],
             ["+", "Expand all sections"],
             ["-", "Collapse all sections"],
-        ].map(function(x) {
-            return "<dt>" +
-                x[0].split(" ")
-                    .map(function(y, index) {
-                        return (index & 1) === 0 ? "<kbd>" + y + "</kbd>" : " " + y + " ";
-                    })
-                    .join("") + "</dt><dd>" + x[1] + "</dd>";
-        }).join("");
+        ].map(x => "<dt>" +
+            x[0].split(" ")
+                .map((y, index) => (index & 1) === 0 ? "<kbd>" + y + "</kbd>" : " " + y + " ")
+                .join("") + "</dt><dd>" + x[1] + "</dd>").join("");
         const div_shortcuts = document.createElement("div");
         addClass(div_shortcuts, "shortcuts");
         div_shortcuts.innerHTML = "<h2>Keyboard Shortcuts</h2><dl>" + shortcuts + "</dl></div>";
@@ -1034,9 +1029,7 @@ function loadCss(cssFileName) {
             "You can look for items with an exact name by putting double quotes around \
              your request: <code>\"string\"</code>",
             "Look for items inside another one by searching for a path: <code>vec::Vec</code>",
-        ].map(function(x) {
-            return "<p>" + x + "</p>";
-        }).join("");
+        ].map(x => "<p>" + x + "</p>").join("");
         const div_infos = document.createElement("div");
         addClass(div_infos, "infos");
         div_infos.innerHTML = "<h2>Search Tricks</h2>" + infos;
@@ -1056,7 +1049,7 @@ function loadCss(cssFileName) {
         popup.appendChild(container);
         insertAfter(popup, document.querySelector("main"));
         // So that it's only built once and then it'll do nothing when called!
-        buildHelperPopup = function() {};
+        buildHelperPopup = () => {};
     };
 
     onHashChange(null);
@@ -1067,11 +1060,11 @@ function loadCss(cssFileName) {
 (function () {
     let reset_button_timeout = null;
 
-    window.copy_path = function(but) {
+    window.copy_path = but => {
         const parent = but.parentElement;
         const path = [];
 
-        onEach(parent.childNodes, function(child) {
+        onEach(parent.childNodes, child => {
             if (child.tagName === 'A') {
                 path.push(child.textContent);
             }
@@ -1097,7 +1090,7 @@ function loadCss(cssFileName) {
             tmp = document.createTextNode('✓');
             but.appendChild(tmp);
         } else {
-            onEachLazy(but.childNodes, function(e) {
+            onEachLazy(but.childNodes, e => {
                 if (e.nodeType === Node.TEXT_NODE) {
                     tmp = e;
                     return true;
diff --git a/src/librustdoc/html/static/js/scrape-examples.js b/src/librustdoc/html/static/js/scrape-examples.js
index 865ed7190f3..491b3950ae6 100644
--- a/src/librustdoc/html/static/js/scrape-examples.js
+++ b/src/librustdoc/html/static/js/scrape-examples.js
@@ -1,6 +1,7 @@
 /* eslint-env es6 */
 /* eslint no-var: "error" */
 /* eslint prefer-const: "error" */
+/* eslint prefer-arrow-callback: "error" */
 /* global addClass, hasClass, removeClass, onEachLazy */
 
 (function () {
@@ -38,7 +39,7 @@
 
         if (locs.length > 1) {
             // Toggle through list of examples in a given file
-            const onChangeLoc = function(changeIndex) {
+            const onChangeLoc = changeIndex => {
                 removeClass(highlights[locIndex], 'focus');
                 changeIndex();
                 scrollToLoc(example, locs[locIndex][0]);
@@ -52,15 +53,15 @@
             };
 
             example.querySelector('.prev')
-                .addEventListener('click', function() {
-                    onChangeLoc(function() {
+                .addEventListener('click', () => {
+                    onChangeLoc(() => {
                         locIndex = (locIndex - 1 + locs.length) % locs.length;
                     });
                 });
 
             example.querySelector('.next')
-                .addEventListener('click', function() {
-                    onChangeLoc(function() {
+                .addEventListener('click', () => {
+                    onChangeLoc(() => {
                         locIndex = (locIndex + 1) % locs.length;
                     });
                 });
@@ -68,7 +69,7 @@
 
         const expandButton = example.querySelector('.expand');
         if (expandButton) {
-            expandButton.addEventListener('click', function () {
+            expandButton.addEventListener('click', () => {
                 if (hasClass(example, "expanded")) {
                     removeClass(example, "expanded");
                     scrollToLoc(example, locs[0][0]);
@@ -84,22 +85,22 @@
 
     const firstExamples = document.querySelectorAll('.scraped-example-list > .scraped-example');
     onEachLazy(firstExamples, updateScrapedExample);
-    onEachLazy(document.querySelectorAll('.more-examples-toggle'), function(toggle) {
+    onEachLazy(document.querySelectorAll('.more-examples-toggle'), toggle => {
         // Allow users to click the left border of the <details> section to close it,
         // since the section can be large and finding the [+] button is annoying.
         onEachLazy(toggle.querySelectorAll('.toggle-line, .hide-more'), button => {
-            button.addEventListener('click', function() {
+            button.addEventListener('click', () => {
                 toggle.open = false;
             });
         });
 
         const moreExamples = toggle.querySelectorAll('.scraped-example');
-        toggle.querySelector('summary').addEventListener('click', function() {
+        toggle.querySelector('summary').addEventListener('click', () => {
             // Wrapping in setTimeout ensures the update happens after the elements are actually
             // visible. This is necessary since updateScrapedExample calls scrollToLoc which
             // depends on offsetHeight, a property that requires an element to be visible to
             // compute correctly.
-            setTimeout(function() { onEachLazy(moreExamples, updateScrapedExample); });
+            setTimeout(() => { onEachLazy(moreExamples, updateScrapedExample); });
         }, {once: true});
     });
 })();
diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js
index 84600fa3e09..60ad431ba7a 100644
--- a/src/librustdoc/html/static/js/search.js
+++ b/src/librustdoc/html/static/js/search.js
@@ -1,10 +1,11 @@
 /* eslint-env es6 */
 /* eslint no-var: "error" */
 /* eslint prefer-const: "error" */
+/* eslint prefer-arrow-callback: "error" */
 /* global addClass, getNakedUrl, getSettingValue, hasOwnPropertyRustdoc, initSearch, onEach */
 /* global onEachLazy, removeClass, searchState, browserSupportsHistoryApi */
 
-(function() {
+(function () {
 // This mapping table should match the discriminants of
 // `rustdoc::formats::item_type::ItemType` type in Rust.
 const itemTypes = [
@@ -46,7 +47,7 @@ function printTab(nb) {
         searchState.currentTab = nb;
     }
     let nb_copy = nb;
-    onEachLazy(document.getElementById("titles").childNodes, function(elem) {
+    onEachLazy(document.getElementById("titles").childNodes, elem => {
         if (nb_copy === 0) {
             addClass(elem, "selected");
         } else {
@@ -54,7 +55,7 @@ function printTab(nb) {
         }
         nb_copy -= 1;
     });
-    onEachLazy(document.getElementById("results").childNodes, function(elem) {
+    onEachLazy(document.getElementById("results").childNodes, elem => {
         if (nb === 0) {
             addClass(elem, "active");
         } else {
@@ -100,7 +101,7 @@ function levenshtein(s1, s2) {
     return s1_len + s2_len;
 }
 
-window.initSearch = function(rawSearchIndex) {
+window.initSearch = rawSearchIndex => {
     const MAX_LEV_DISTANCE = 3;
     const MAX_RESULTS = 200;
     const GENERICS_DATA = 2;
@@ -774,7 +775,7 @@ window.initSearch = function(rawSearchIndex) {
                 return [];
             }
 
-            results.sort(function(aaa, bbb) {
+            results.sort((aaa, bbb) => {
                 let a, b;
 
                 // sort by exact match with regard to the last word (mismatch goes later)
@@ -978,9 +979,8 @@ window.initSearch = function(rawSearchIndex) {
                     if (elem.generics.length === 0) {
                         const checkGeneric = (row.length > GENERICS_DATA &&
                             row[GENERICS_DATA].length > 0);
-                        if (checkGeneric && row[GENERICS_DATA].findIndex(function(tmp_elem) {
-                            return tmp_elem[NAME] === elem.name;
-                        }) !== -1) {
+                        if (checkGeneric && row[GENERICS_DATA]
+                            .findIndex(tmp_elem => tmp_elem[NAME] === elem.name) !== -1) {
                             return 0;
                         }
                     }
@@ -1169,7 +1169,7 @@ window.initSearch = function(rawSearchIndex) {
                     }
                 }
             } else {
-                Object.keys(ALIASES).forEach(function(crate) {
+                Object.keys(ALIASES).forEach(crate => {
                     if (ALIASES[crate][lowerQuery]) {
                         const pushTo = crate === window.currentCrate ? crateAliases : aliases;
                         const query_aliases = ALIASES[crate][lowerQuery];
@@ -1180,7 +1180,7 @@ window.initSearch = function(rawSearchIndex) {
                 });
             }
 
-            const sortFunc = function(aaa, bbb) {
+            const sortFunc = (aaa, bbb) => {
                 if (aaa.path < bbb.path) {
                     return 1;
                 } else if (aaa.path === bbb.path) {
@@ -1191,7 +1191,7 @@ window.initSearch = function(rawSearchIndex) {
             crateAliases.sort(sortFunc);
             aliases.sort(sortFunc);
 
-            const pushFunc = function(alias) {
+            const pushFunc = alias => {
                 alias.alias = query;
                 const res = buildHrefAndPath(alias);
                 alias.displayPath = pathSplitter(res[0]);
@@ -1579,7 +1579,7 @@ window.initSearch = function(rawSearchIndex) {
         if (array.length > 0) {
             output.className = "search-results " + extraClass;
 
-            array.forEach(function(item) {
+            array.forEach(item => {
                 const name = item.name;
                 const type = itemTypes[item.ty];
 
@@ -1746,9 +1746,9 @@ window.initSearch = function(rawSearchIndex) {
         searchState.focusedByTab = [null, null, null];
         searchState.showResults(search);
         const elems = document.getElementById("titles").childNodes;
-        elems[0].onclick = function() { printTab(0); };
-        elems[1].onclick = function() { printTab(1); };
-        elems[2].onclick = function() { printTab(2); };
+        elems[0].onclick = () => { printTab(0); };
+        elems[1].onclick = () => { printTab(1); };
+        elems[2].onclick = () => { printTab(2); };
         printTab(currentTab);
     }
 
@@ -1977,7 +1977,7 @@ window.initSearch = function(rawSearchIndex) {
     }
 
     function registerSearchEvents() {
-        const searchAfter500ms = function() {
+        const searchAfter500ms = () => {
             searchState.clearInputTimeout();
             if (searchState.input.value.length === 0) {
                 if (browserSupportsHistoryApi()) {
@@ -1992,7 +1992,7 @@ window.initSearch = function(rawSearchIndex) {
         searchState.input.onkeyup = searchAfter500ms;
         searchState.input.oninput = searchAfter500ms;
         document.getElementsByClassName("search-form")[0].onsubmit = onSearchSubmit;
-        searchState.input.onchange = function(e) {
+        searchState.input.onchange = e => {
             if (e.target !== document.activeElement) {
                 // To prevent doing anything when it's from a blur event.
                 return;
@@ -2006,7 +2006,7 @@ window.initSearch = function(rawSearchIndex) {
         };
         searchState.input.onpaste = searchState.input.onchange;
 
-        searchState.outputElement().addEventListener("keydown", function(e) {
+        searchState.outputElement().addEventListener("keydown", e => {
             // We only handle unmodified keystrokes here. We don't want to interfere with,
             // for instance, alt-left and alt-right for history navigation.
             if (e.altKey || e.ctrlKey || e.shiftKey || e.metaKey) {
@@ -2041,18 +2041,18 @@ window.initSearch = function(rawSearchIndex) {
             }
         });
 
-        searchState.input.addEventListener("keydown", function(e) {
+        searchState.input.addEventListener("keydown", e => {
             if (e.which === 40) { // down
                 focusSearchResult();
                 e.preventDefault();
             }
         });
 
-        searchState.input.addEventListener("focus", function() {
+        searchState.input.addEventListener("focus", () => {
             putBackSearch();
         });
 
-        searchState.input.addEventListener("blur", function() {
+        searchState.input.addEventListener("blur", () => {
             searchState.input.placeholder = searchState.input.origPlaceholder;
         });
 
@@ -2062,7 +2062,7 @@ window.initSearch = function(rawSearchIndex) {
             // Store the previous <title> so we can revert back to it later.
             const previousTitle = document.title;
 
-            window.addEventListener("popstate", function(e) {
+            window.addEventListener("popstate", e => {
                 const params = searchState.getQueryStringParams();
                 // Revert to the previous title manually since the History
                 // API ignores the title parameter.
@@ -2098,7 +2098,7 @@ window.initSearch = function(rawSearchIndex) {
         // This was an interaction between the back-forward cache and our handlers
         // that try to sync state between the URL and the search input. To work around it,
         // do a small amount of re-init on page show.
-        window.onpageshow = function(){
+        window.onpageshow = () => {
             const qSearch = searchState.getQueryStringParams().search;
             if (searchState.input.value === "" && qSearch) {
                 searchState.input.value = qSearch;
diff --git a/src/librustdoc/html/static/js/settings.js b/src/librustdoc/html/static/js/settings.js
index a2f8d56fb32..43b24245ab2 100644
--- a/src/librustdoc/html/static/js/settings.js
+++ b/src/librustdoc/html/static/js/settings.js
@@ -1,6 +1,7 @@
 /* eslint-env es6 */
 /* eslint no-var: "error" */
 /* eslint prefer-const: "error" */
+/* eslint prefer-arrow-callback: "error" */
 // Local js definitions:
 /* global getSettingValue, getVirtualKey, updateLocalStorage, updateSystemTheme, loadCss */
 /* global addClass, removeClass, onEach, onEachLazy, NOT_DISPLAYED_ID */
@@ -60,7 +61,7 @@
 
     function setEvents(settingsElement) {
         updateLightAndDark();
-        onEachLazy(settingsElement.getElementsByClassName("slider"), function(elem) {
+        onEachLazy(settingsElement.getElementsByClassName("slider"), elem => {
             const toggle = elem.previousElementSibling;
             const settingId = toggle.id;
             const settingValue = getSettingValue(settingId);
@@ -73,7 +74,7 @@
             toggle.onkeyup = handleKey;
             toggle.onkeyrelease = handleKey;
         });
-        onEachLazy(settingsElement.getElementsByClassName("select-wrapper"), function(elem) {
+        onEachLazy(settingsElement.getElementsByClassName("select-wrapper"), elem => {
             const select = elem.getElementsByTagName("select")[0];
             const settingId = select.id;
             const settingValue = getSettingValue(settingId);
@@ -84,13 +85,13 @@
                 changeSetting(this.id, this.value);
             };
         });
-        onEachLazy(settingsElement.querySelectorAll("input[type=\"radio\"]"), function(elem) {
+        onEachLazy(settingsElement.querySelectorAll("input[type=\"radio\"]"), elem => {
             const settingId = elem.name;
             const settingValue = getSettingValue(settingId);
             if (settingValue !== null && settingValue !== "null") {
                 elem.checked = settingValue === elem.value;
             }
-            elem.addEventListener("change", function(ev) {
+            elem.addEventListener("change", ev => {
                 changeSetting(ev.target.name, ev.target.value);
             });
         });
@@ -118,7 +119,7 @@
                 output += `<div class="radio-line" id="${js_data_name}">\
                         <span class="setting-name">${setting_name}</span>\
                         <div class="choices">`;
-                onEach(setting["options"], function(option) {
+                onEach(setting["options"], option => {
                     const checked = option === setting["default"] ? " checked" : "";
 
                     output += `<label for="${js_data_name}-${option}" class="choice">\
@@ -265,7 +266,7 @@
     }
 
     // We now wait a bit for the web browser to end re-computing the DOM...
-    setTimeout(function() {
+    setTimeout(() => {
         setEvents(settingsMenu);
         // The setting menu is already displayed if we're on the settings page.
         if (!isSettingsPage) {
diff --git a/src/librustdoc/html/static/js/source-script.js b/src/librustdoc/html/static/js/source-script.js
index 6aee0da69f8..290bf40a8f5 100644
--- a/src/librustdoc/html/static/js/source-script.js
+++ b/src/librustdoc/html/static/js/source-script.js
@@ -1,6 +1,7 @@
 /* eslint-env es6 */
 /* eslint no-var: "error" */
 /* eslint prefer-const: "error" */
+/* eslint prefer-arrow-callback: "error" */
 
 // From rust:
 /* global search, sourcesIndex */
@@ -8,7 +9,7 @@
 // Local js definitions:
 /* global addClass, getCurrentValue, hasClass, onEachLazy, removeClass, browserSupportsHistoryApi */
 /* global updateLocalStorage */
-(function() {
+(function () {
 
 function getCurrentFilePath() {
     const parts = window.location.pathname.split("/");
@@ -32,7 +33,7 @@ function createDirEntry(elem, parent, fullPath, currentFile, hasFoundFile) {
 
     fullPath += elem["name"] + "/";
 
-    name.onclick = function() {
+    name.onclick = () => {
         if (hasClass(this, "expand")) {
             removeClass(this, "expand");
         } else {
@@ -134,7 +135,7 @@ function createSourceSidebar() {
     title.className = "title";
     title.innerText = "Files";
     sidebar.appendChild(title);
-    Object.keys(sourcesIndex).forEach(function(key) {
+    Object.keys(sourcesIndex).forEach(key => {
         sourcesIndex[key].name = key;
         hasFoundFile = createDirEntry(sourcesIndex[key], sidebar, "",
                                       currentFile, hasFoundFile);
@@ -175,8 +176,8 @@ function highlightSourceLines(match) {
     if (x) {
         x.scrollIntoView();
     }
-    onEachLazy(document.getElementsByClassName("line-numbers"), function(e) {
-        onEachLazy(e.getElementsByTagName("span"), function(i_e) {
+    onEachLazy(document.getElementsByClassName("line-numbers"), e => {
+        onEachLazy(e.getElementsByTagName("span"), i_e => {
             removeClass(i_e, "line-highlighted");
         });
     });
@@ -189,10 +190,10 @@ function highlightSourceLines(match) {
     }
 }
 
-const handleSourceHighlight = (function() {
+const handleSourceHighlight = (function () {
     let prev_line_id = 0;
 
-    const set_fragment = function(name) {
+    const set_fragment = name => {
         const x = window.scrollX,
             y = window.scrollY;
         if (browserSupportsHistoryApi()) {
@@ -205,7 +206,7 @@ const handleSourceHighlight = (function() {
         window.scrollTo(x, y);
     };
 
-    return function(ev) {
+    return ev => {
         let cur_line_id = parseInt(ev.target.id, 10);
         ev.preventDefault();
 
@@ -226,14 +227,14 @@ const handleSourceHighlight = (function() {
     };
 }());
 
-window.addEventListener("hashchange", function() {
+window.addEventListener("hashchange", () => {
     const match = window.location.hash.match(lineNumbersRegex);
     if (match) {
         return highlightSourceLines(match);
     }
 });
 
-onEachLazy(document.getElementsByClassName("line-numbers"), function(el) {
+onEachLazy(document.getElementsByClassName("line-numbers"), el => {
     el.addEventListener("click", handleSourceHighlight);
 });
 
diff --git a/src/librustdoc/html/static/js/storage.js b/src/librustdoc/html/static/js/storage.js
index ae670ed9894..913fc278eb3 100644
--- a/src/librustdoc/html/static/js/storage.js
+++ b/src/librustdoc/html/static/js/storage.js
@@ -1,6 +1,7 @@
 /* eslint-env es6 */
 /* eslint no-var: "error" */
 /* eslint prefer-const: "error" */
+/* eslint prefer-arrow-callback: "error" */
 
 const darkThemes = ["dark", "ayu"];
 window.currentTheme = document.getElementById("themeStyle");
@@ -139,11 +140,11 @@ function switchTheme(styleElem, mainStyleElem, newTheme, saveTheme) {
 
     let found = false;
     if (savedHref.length === 0) {
-        onEachLazy(document.getElementsByTagName("link"), function(el) {
+        onEachLazy(document.getElementsByTagName("link"), el => {
             savedHref.push(el.href);
         });
     }
-    onEach(savedHref, function(el) {
+    onEach(savedHref, el => {
         if (el === newHref) {
             found = true;
             return true;
@@ -170,10 +171,10 @@ function useSystemTheme(value) {
     }
 }
 
-const updateSystemTheme = (function() {
+const updateSystemTheme = (function () {
     if (!window.matchMedia) {
         // fallback to the CSS computed value
-        return function() {
+        return () => {
             const cssTheme = getComputedStyle(document.documentElement)
                 .getPropertyValue('content');
 
@@ -190,7 +191,7 @@ const updateSystemTheme = (function() {
     const mql = window.matchMedia("(prefers-color-scheme: dark)");
 
     function handlePreferenceChange(mql) {
-        const use = function(theme) {
+        const use = theme => {
             switchTheme(window.currentTheme, window.mainTheme, theme, true);
         };
         // maybe the user has disabled the setting in the meantime!
@@ -214,7 +215,7 @@ const updateSystemTheme = (function() {
 
     mql.addListener(handlePreferenceChange);
 
-    return function() {
+    return () => {
         handlePreferenceChange(mql);
     };
 })();
@@ -252,7 +253,7 @@ if (getSettingValue("use-system-theme") !== "false" && window.matchMedia) {
 // For some reason, if we try to change the theme while the `pageshow` event is
 // running, it sometimes fails to take effect. The problem manifests on Chrome,
 // specifically when talking to a remote website with no caching.
-window.addEventListener("pageshow", function(ev) {
+window.addEventListener("pageshow", ev => {
     if (ev.persisted) {
         setTimeout(switchToSavedTheme, 0);
     }