Convert require to import: rjquery, timeslider, underscore

- Convert const X = require('Y') to import X from 'Y.js'
- Convert const {A, B} = require('Y') to import {A, B} from 'Y.js'
- Add .js extensions to relative imports
- Keep external packages without .js (e.g., 'tinycon/tinycon', 'underscore')
- Convert exports.X = Y to export {X}
- Convert module.exports to export default

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/static/js/rjquery.ts

@@ -1,6 +1,8 @@
 // @ts-nocheck
 'use strict';
 // Provides a require'able version of jQuery without leaking $ and jQuery;
-window.$ = require('./vendors/jquery');
+import $ from './vendors/jquery.js';
+window.$ = $;
 const jq = window.$.noConflict(true);
-exports.jQuery = exports.$ = jq;
+
+export {jq as jQuery, jq as $};

src/static/js/timeslider.ts

@@ -25,13 +25,13 @@
 
 // These jQuery things should create local references, but for now `require()`
 // assigns to the global `$` and augments it with plugins.
-require('./vendors/jquery');
+import './vendors/jquery.js';
 
-import {randomString, Cookies} from "./pad_utils";
-const hooks = require('./pluginfw/hooks');
-import padutils from './pad_utils'
-const socketio = require('./socketio');
-import html10n from '../js/vendors/html10n'
+import {randomString, Cookies} from "./pad_utils.js";
+import hooks from './pluginfw/hooks.js';
+import padutils from './pad_utils.js'
+import socketio from './socketio.js';
+import html10n from '../js/vendors/html10n.js'
 let token, padId, exportLinks, socket, changesetLoader, BroadcastSlider;
 let cp = '';
 const playbackSpeedCookie = 'timesliderPlaybackSpeed';
@@ -222,5 +222,5 @@ const handleClientVars = (message) => {
   });
 };
 
-exports.baseURL = '';
-exports.init = init;
+export const baseURL = '';
+export {init};

src/static/js/underscore.ts

@@ -1,4 +1,6 @@
 // @ts-nocheck
 'use strict';
 
-module.exports = require('underscore');
+import _ from 'underscore';
+
+export default _;