diff --git a/src/static/js/pluginfw/hooks.js b/src/static/js/pluginfw/hooks.js
index 6243a9305..e61079eb6 100644
--- a/src/static/js/pluginfw/hooks.js
+++ b/src/static/js/pluginfw/hooks.js
@@ -1,4 +1,4 @@
-/* global exports, require */
+'use strict';
 
 const _ = require('underscore');
 const pluginDefs = require('./plugin_defs');
@@ -15,30 +15,28 @@ exports.deprecationNotices = {};
 
 const deprecationWarned = {};
 
-function checkDeprecation(hook) {
+const checkDeprecation = (hook) => {
   const notice = exports.deprecationNotices[hook.hook_name];
   if (notice == null) return;
   if (deprecationWarned[hook.hook_fn_name]) return;
   console.warn(`${hook.hook_name} hook used by the ${hook.part.plugin} plugin ` +
                `(${hook.hook_fn_name}) is deprecated: ${notice}`);
   deprecationWarned[hook.hook_fn_name] = true;
-}
+};
 
 exports.bubbleExceptions = true;
 
-const hookCallWrapper = function (hook, hook_name, args, cb) {
-  if (cb === undefined) cb = function (x) { return x; };
+const hookCallWrapper = (hook, hook_name, args, cb) => {
+  if (cb === undefined) cb = (x) => x;
 
   checkDeprecation(hook);
 
   // Normalize output to list for both sync and async cases
-  const normalize = function (x) {
+  const normalize = (x) => {
     if (x === undefined) return [];
     return x;
   };
-  const normalizedhook = function () {
-    return normalize(hook.hook_fn(hook_name, args, (x) => cb(normalize(x))));
-  };
+  const normalizedhook = () => normalize(hook.hook_fn(hook_name, args, (x) => cb(normalize(x))));
 
   if (exports.bubbleExceptions) {
     return normalizedhook();
@@ -51,7 +49,7 @@ const hookCallWrapper = function (hook, hook_name, args, cb) {
   }
 };
 
-exports.syncMapFirst = function (lst, fn) {
+exports.syncMapFirst = (lst, fn) => {
   let i;
   let result;
   for (i = 0; i < lst.length; i++) {
@@ -61,11 +59,11 @@ exports.syncMapFirst = function (lst, fn) {
   return [];
 };
 
-exports.mapFirst = function (lst, fn, cb, predicate) {
+exports.mapFirst = (lst, fn, cb, predicate) => {
   if (predicate == null) predicate = (x) => (x != null && x.length > 0);
   let i = 0;
 
-  var next = function () {
+  const next = () => {
     if (i >= lst.length) return cb(null, []);
     fn(lst[i++], (err, result) => {
       if (err) return cb(err);
@@ -104,7 +102,7 @@ exports.mapFirst = function (lst, fn, cb, predicate) {
 //
 // See the tests in tests/backend/specs/hooks.js for examples of supported and prohibited behaviors.
 //
-function callHookFnSync(hook, context) {
+const callHookFnSync = (hook, context) => {
   checkDeprecation(hook);
 
   // This var is used to keep track of whether the hook function already settled.
@@ -190,7 +188,7 @@ function callHookFnSync(hook, context) {
 
   settle(null, val, 'returned value');
   return outcome.val;
-}
+};
 
 // Invokes all registered hook functions synchronously.
 //
@@ -203,7 +201,7 @@ function callHookFnSync(hook, context) {
 //     1. Collect all values returned by the hook functions into an array.
 //     2. Convert each `undefined` entry into `[]`.
 //     3. Flatten one level.
-exports.callAll = function (hookName, context) {
+exports.callAll = (hookName, context) => {
   if (context == null) context = {};
   const hooks = pluginDefs.hooks[hookName] || [];
   return _.flatten(hooks.map((hook) => {
@@ -248,7 +246,7 @@ exports.callAll = function (hookName, context) {
 //
 // See the tests in tests/backend/specs/hooks.js for examples of supported and prohibited behaviors.
 //
-async function callHookFnAsync(hook, context) {
+const callHookFnAsync = async (hook, context) => {
   checkDeprecation(hook);
   return await new Promise((resolve, reject) => {
     // This var is used to keep track of whether the hook function already settled.
@@ -326,7 +324,7 @@ async function callHookFnAsync(hook, context) {
         (val) => settle(null, val, 'returned value'),
         (err) => settle(err, null, 'Promise rejection'));
   });
-}
+};
 
 // Invokes all registered hook functions asynchronously.
 //
@@ -350,20 +348,22 @@ exports.aCallAll = async (hookName, context, cb) => {
   const hooks = pluginDefs.hooks[hookName] || [];
   let resultsPromise = Promise.all(hooks.map((hook) => callHookFnAsync(hook, context)
   // `undefined` (but not `null`!) is treated the same as [].
-      .then((result) => (result === undefined) ? [] : result))).then((results) => _.flatten(results, 1));
+      .then((result) => (result === undefined) ? [] : result)))
+      .then((results) => _.flatten(results, 1));
   if (cb != null) resultsPromise = resultsPromise.then((val) => cb(null, val), cb);
   return await resultsPromise;
 };
 
-exports.callFirst = function (hook_name, args) {
+exports.callFirst = (hook_name, args) => {
   if (!args) args = {};
   if (pluginDefs.hooks[hook_name] === undefined) return [];
-  return exports.syncMapFirst(pluginDefs.hooks[hook_name], (hook) => hookCallWrapper(hook, hook_name, args));
+  return exports.syncMapFirst(pluginDefs.hooks[hook_name],
+      (hook) => hookCallWrapper(hook, hook_name, args));
 };
 
-function aCallFirst(hook_name, args, cb, predicate) {
+const aCallFirst = (hook_name, args, cb, predicate) => {
   if (!args) args = {};
-  if (!cb) cb = function () {};
+  if (!cb) cb = () => {};
   if (pluginDefs.hooks[hook_name] === undefined) return cb(null, []);
   exports.mapFirst(
       pluginDefs.hooks[hook_name],
@@ -373,10 +373,10 @@ function aCallFirst(hook_name, args, cb, predicate) {
       cb,
       predicate
   );
-}
+};
 
 /* return a Promise if cb is not supplied */
-exports.aCallFirst = function (hook_name, args, cb, predicate) {
+exports.aCallFirst = (hook_name, args, cb, predicate) => {
   if (cb === undefined) {
     return new Promise((resolve, reject) => {
       aCallFirst(hook_name, args, (err, res) => err ? reject(err) : resolve(res), predicate);
@@ -386,10 +386,10 @@ exports.aCallFirst = function (hook_name, args, cb, predicate) {
   }
 };
 
-exports.callAllStr = function (hook_name, args, sep, pre, post) {
-  if (sep == undefined) sep = '';
-  if (pre == undefined) pre = '';
-  if (post == undefined) post = '';
+exports.callAllStr = (hook_name, args, sep, pre, post) => {
+  if (sep === undefined) sep = '';
+  if (pre === undefined) pre = '';
+  if (post === undefined) post = '';
   const newCallhooks = [];
   const callhooks = exports.callAll(hook_name, args);
   for (let i = 0, ii = callhooks.length; i < ii; i++) {
diff --git a/src/static/js/pluginfw/installer.js b/src/static/js/pluginfw/installer.js
index 7d29b91b1..ae5c06e10 100644
--- a/src/static/js/pluginfw/installer.js
+++ b/src/static/js/pluginfw/installer.js
@@ -1,6 +1,8 @@
+'use strict';
+
 const log4js = require('log4js');
-const plugins = require('ep_etherpad-lite/static/js/pluginfw/plugins');
-const hooks = require('ep_etherpad-lite/static/js/pluginfw/hooks');
+const plugins = require('./plugins');
+const hooks = require('./hooks');
 const npm = require('npm');
 const request = require('request');
 const util = require('util');
@@ -13,22 +15,22 @@ const loadNpm = async () => {
   npm.on('log', log4js.getLogger('npm').log);
 };
 
+const onAllTasksFinished = () => {
+  hooks.aCallAll('restartServer', {}, () => {});
+};
+
 let tasks = 0;
 
 function wrapTaskCb(cb) {
   tasks++;
 
-  return function () {
-    cb && cb.apply(this, arguments);
+  return function (...args) {
+    cb && cb.apply(this, args);
     tasks--;
-    if (tasks == 0) onAllTasksFinished();
+    if (tasks === 0) onAllTasksFinished();
   };
 }
 
-function onAllTasksFinished() {
-  hooks.aCallAll('restartServer', {}, () => {});
-}
-
 exports.uninstall = async (pluginName, cb = null) => {
   cb = wrapTaskCb(cb);
   try {
@@ -60,7 +62,7 @@ exports.install = async (pluginName, cb = null) => {
 exports.availablePlugins = null;
 let cacheTimestamp = 0;
 
-exports.getAvailablePlugins = function (maxCacheAge) {
+exports.getAvailablePlugins = (maxCacheAge) => {
   const nowTimestamp = Math.round(Date.now() / 1000);
 
   return new Promise((resolve, reject) => {
@@ -87,31 +89,33 @@ exports.getAvailablePlugins = function (maxCacheAge) {
 };
 
 
-exports.search = function (searchTerm, maxCacheAge) {
-  return exports.getAvailablePlugins(maxCacheAge).then((results) => {
-    const res = {};
+exports.search = (searchTerm, maxCacheAge) => exports.getAvailablePlugins(maxCacheAge).then(
+    (results) => {
+      const res = {};
 
-    if (searchTerm) {
-      searchTerm = searchTerm.toLowerCase();
-    }
-
-    for (const pluginName in results) {
-      // for every available plugin
-      if (pluginName.indexOf(plugins.prefix) != 0) continue; // TODO: Also search in keywords here!
-
-      if (searchTerm && !~results[pluginName].name.toLowerCase().indexOf(searchTerm) &&
-         (typeof results[pluginName].description !== 'undefined' && !~results[pluginName].description.toLowerCase().indexOf(searchTerm))
-      ) {
-        if (typeof results[pluginName].description === 'undefined') {
-          console.debug('plugin without Description: %s', results[pluginName].name);
-        }
-
-        continue;
+      if (searchTerm) {
+        searchTerm = searchTerm.toLowerCase();
       }
 
-      res[pluginName] = results[pluginName];
-    }
+      for (const pluginName in results) {
+        // for every available plugin
+        // TODO: Also search in keywords here!
+        if (pluginName.indexOf(plugins.prefix) !== 0) continue;
 
-    return res;
-  });
-};
+        if (searchTerm && !~results[pluginName].name.toLowerCase().indexOf(searchTerm) &&
+           (typeof results[pluginName].description !== 'undefined' &&
+              !~results[pluginName].description.toLowerCase().indexOf(searchTerm))
+        ) {
+          if (typeof results[pluginName].description === 'undefined') {
+            console.debug('plugin without Description: %s', results[pluginName].name);
+          }
+
+          continue;
+        }
+
+        res[pluginName] = results[pluginName];
+      }
+
+      return res;
+    }
+);
diff --git a/src/static/js/pluginfw/plugin_defs.js b/src/static/js/pluginfw/plugin_defs.js
index 95bbcb95c..768d99c3e 100644
--- a/src/static/js/pluginfw/plugin_defs.js
+++ b/src/static/js/pluginfw/plugin_defs.js
@@ -1,3 +1,5 @@
+'use strict';
+
 // This module contains processed plugin definitions. The data structures in this file are set by
 // plugins.js (server) or client_plugins.js (client).
 
diff --git a/src/static/js/pluginfw/plugins.js b/src/static/js/pluginfw/plugins.js
index 52fbdd271..4acdee7bd 100644
--- a/src/static/js/pluginfw/plugins.js
+++ b/src/static/js/pluginfw/plugins.js
@@ -1,6 +1,7 @@
+'use strict';
+
 const fs = require('fs').promises;
 const hooks = require('./hooks');
-const npm = require('npm/lib/npm.js');
 const readInstalled = require('./read-installed.js');
 const path = require('path');
 const tsort = require('./tsort');
@@ -13,11 +14,9 @@ const defs = require('./plugin_defs');
 
 exports.prefix = 'ep_';
 
-exports.formatPlugins = function () {
-  return _.keys(defs.plugins).join(', ');
-};
+exports.formatPlugins = () => Object.keys(defs.plugins).join(', ');
 
-exports.formatPluginsWithVersion = function () {
+exports.formatPluginsWithVersion = () => {
   const plugins = [];
   _.forEach(defs.plugins, (plugin) => {
     if (plugin.package.name !== 'ep_etherpad-lite') {
@@ -28,17 +27,16 @@ exports.formatPluginsWithVersion = function () {
   return plugins.join(', ');
 };
 
-exports.formatParts = function () {
-  return _.map(defs.parts, (part) => part.full_name).join('\n');
-};
+exports.formatParts = () => _.map(defs.parts, (part) => part.full_name).join('\n');
 
-exports.formatHooks = function (hook_set_name) {
+exports.formatHooks = (hook_set_name) => {
   const res = [];
   const hooks = pluginUtils.extractHooks(defs.parts, hook_set_name || 'hooks');
 
   _.chain(hooks).keys().forEach((hook_name) => {
     _.forEach(hooks[hook_name], (hook) => {
-      res.push(`<dt>${hook.hook_name}</dt><dd>${hook.hook_fn_name} from ${hook.part.full_name}</dd>`);
+      res.push(`<dt>${hook.hook_name}</dt><dd>${hook.hook_fn_name} ` +
+               `from ${hook.part.full_name}</dd>`);
     });
   });
   return `<dl>${res.join('\n')}</dl>`;
@@ -57,7 +55,7 @@ const callInit = async () => {
   }));
 };
 
-exports.pathNormalization = function (part, hook_fn_name, hook_name) {
+exports.pathNormalization = (part, hook_fn_name, hook_name) => {
   const tmp = hook_fn_name.split(':'); // hook_fn_name might be something like 'C:\\foo.js:myFunc'.
   // If there is a single colon assume it's 'filename:funcname' not 'C:\\filename'.
   const functionName = (tmp.length > 1 ? tmp.pop() : null) || hook_name;
@@ -67,7 +65,7 @@ exports.pathNormalization = function (part, hook_fn_name, hook_name) {
   return `${fileName}:${functionName}`;
 };
 
-exports.update = async function () {
+exports.update = async () => {
   const packages = await exports.getPackages();
   const parts = {}; // Key is full name. sortParts converts this into a topologically sorted array.
   const plugins = {};
@@ -83,13 +81,14 @@ exports.update = async function () {
   await callInit();
 };
 
-exports.getPackages = async function () {
-  // Load list of installed NPM packages, flatten it to a list, and filter out only packages with names that
+exports.getPackages = async () => {
+  // Load list of installed NPM packages, flatten it to a list,
+  // and filter out only packages with names that
   const dir = settings.root;
   const data = await util.promisify(readInstalled)(dir);
 
   const packages = {};
-  function flatten(deps) {
+  const flatten = (deps) => {
     _.chain(deps).keys().each((name) => {
       if (name.indexOf(exports.prefix) === 0) {
         packages[name] = _.clone(deps[name]);
@@ -102,7 +101,7 @@ exports.getPackages = async function () {
       // I don't think we need recursion
       // if (deps[name].dependencies !== undefined) flatten(deps[name].dependencies);
     });
-  }
+  };
 
   const tmp = {};
   tmp[data.name] = data;
@@ -110,7 +109,7 @@ exports.getPackages = async function () {
   return packages;
 };
 
-async function loadPlugin(packages, plugin_name, plugins, parts) {
+const loadPlugin = async (packages, plugin_name, plugins, parts) => {
   const plugin_path = path.resolve(packages[plugin_name].path, 'ep.json');
   try {
     const data = await fs.readFile(plugin_path);
@@ -129,9 +128,9 @@ async function loadPlugin(packages, plugin_name, plugins, parts) {
   } catch (er) {
     console.error(`Unable to load plugin definition file ${plugin_path}`);
   }
-}
+};
 
-function partsToParentChildList(parts) {
+const partsToParentChildList = (parts) => {
   const res = [];
   _.chain(parts).keys().forEach((name) => {
     _.each(parts[name].post || [], (child_name) => {
@@ -145,15 +144,9 @@ function partsToParentChildList(parts) {
     }
   });
   return res;
-}
+};
 
 // Used only in Node, so no need for _
-function sortParts(parts) {
-  return tsort(
-      partsToParentChildList(parts)
-  ).filter(
-      (name) => parts[name] !== undefined
-  ).map(
-      (name) => parts[name]
-  );
-}
+const sortParts = (parts) => tsort(partsToParentChildList(parts))
+    .filter((name) => parts[name] !== undefined)
+    .map((name) => parts[name]);
diff --git a/src/static/js/pluginfw/shared.js b/src/static/js/pluginfw/shared.js
index 749706812..981cd2558 100644
--- a/src/static/js/pluginfw/shared.js
+++ b/src/static/js/pluginfw/shared.js
@@ -1,3 +1,4 @@
+'use strict';
 const _ = require('underscore');
 const defs = require('./plugin_defs');
 
@@ -8,13 +9,13 @@ const disabledHookReasons = {
   },
 };
 
-function loadFn(path, hookName) {
+const loadFn = (path, hookName) => {
   let functionName;
   const parts = path.split(':');
 
   // on windows: C:\foo\bar:xyz
-  if (parts[0].length == 1) {
-    if (parts.length == 3) {
+  if (parts[0].length === 1) {
+    if (parts.length === 3) {
       functionName = parts.pop();
     }
     path = parts.join(':');
@@ -30,9 +31,9 @@ function loadFn(path, hookName) {
     fn = fn[name];
   });
   return fn;
-}
+};
 
-function extractHooks(parts, hook_set_name, normalizer) {
+const extractHooks = (parts, hook_set_name, normalizer) => {
   const hooks = {};
   _.each(parts, (part) => {
     _.chain(part[hook_set_name] || {})
@@ -50,20 +51,23 @@ function extractHooks(parts, hook_set_name, normalizer) {
 
           const disabledReason = (disabledHookReasons[hook_set_name] || {})[hook_name];
           if (disabledReason) {
-            console.error(`Hook ${hook_set_name}/${hook_name} is disabled. Reason: ${disabledReason}`);
+            console.error(
+                `Hook ${hook_set_name}/${hook_name} is disabled. Reason: ${disabledReason}`);
             console.error(`The hook function ${hook_fn_name} from plugin ${part.plugin} ` +
-                      'will never be called, which may cause the plugin to fail');
-            console.error(`Please update the ${part.plugin} plugin to not use the ${hook_name} hook`);
+                          'will never be called, which may cause the plugin to fail');
+            console.error(
+                `Please update the ${part.plugin} plugin to not use the ${hook_name} hook`);
             return;
           }
-
+          let hook_fn;
           try {
-            var hook_fn = loadFn(hook_fn_name, hook_name);
+            hook_fn = loadFn(hook_fn_name, hook_name);
             if (!hook_fn) {
-              throw 'Not a function';
+              throw new Error('Not a function');
             }
           } catch (exc) {
-            console.error(`Failed to load '${hook_fn_name}' for '${part.full_name}/${hook_set_name}/${hook_name}': ${exc.toString()}`);
+            console.error(`Failed to load '${hook_fn_name}' for ` +
+                          `'${part.full_name}/${hook_set_name}/${hook_name}': ${exc.toString()}`);
           }
           if (hook_fn) {
             if (hooks[hook_name] == null) hooks[hook_name] = [];
@@ -72,7 +76,7 @@ function extractHooks(parts, hook_set_name, normalizer) {
         });
   });
   return hooks;
-}
+};
 
 exports.extractHooks = extractHooks;
 
@@ -88,10 +92,10 @@ exports.extractHooks = extractHooks;
  *   No plugins:   []
  *   Some plugins: [ 'ep_adminpads', 'ep_add_buttons', 'ep_activepads' ]
  */
-exports.clientPluginNames = function () {
+exports.clientPluginNames = () => {
   const client_plugin_names = _.uniq(
       defs.parts
-          .filter((part) => part.hasOwnProperty('client_hooks'))
+          .filter((part) => Object.prototype.hasOwnProperty.call(part, 'client_hooks'))
           .map((part) => `plugin-${part.plugin}`)
   );