Don't seem to be able to have a non-jQuery solution - yet!

amd/src/synhi_cannot_make_work.js

@@ -0,0 +1,73 @@
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * SynHi filter.
+ *
+ * @module     filter_synhi/synhi
+ * @copyright  &copy; 2020-onwards G J Barnard.
+ * @author     G J Barnard - {@link http://moodle.org/user/profile.php?id=442195}
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later.
+ */
+
+//import $ from 'jquery';
+import log from 'core/log';
+
+var done = false;
+
+/**
+ * Init.
+ *
+ * @param {array} data The urls to use.
+ */
+export const init = (data) => {
+    log.debug('SynHi ES6 init');
+    if (!done) {
+        const body = document.getElementsByTagName('body').item(0);
+        let thejs = document.createElement("script");
+        thejs.src = data.thejs;
+        thejs.type = 'text/javascript';
+        thejs.charset = 'utf-8';
+        thejs.defer = false;
+        body.appendChild(thejs);
+        //$body.append('<script type="text/javascript" charset="utf-8" src="' + data.thejs + '"></script>');
+        if (data.theinit) {
+            let theinit = document.createElement("script");
+            theinit.text = data.theinit;
+            theinit.type = 'text/javascript';
+            theinit.charset = 'utf-8';
+            theinit.defer = true;
+            if (document.readyState !== 'loading') {
+                log.debug("SynHi ES6 init DOM content already loaded");
+                body.appendChild(theinit);
+            } else {
+                log.debug("SynHi ES6 init JS DOM content not loaded");
+                document.addEventListener('DOMContentLoaded', function () {
+                    log.debug("SynHi ES6 init JS DOM content loaded");
+                    body.appendChild(theinit);  // E.g. Enlighter not found, so code runs before JS file is known about.
+                });
+            }
+            //$body.append('<script type="text/javascript" charset="utf-8">' + data.theinit + '</script>');
+        }
+        let thecss = document.createElement("link");
+        thecss.href = data.thecss;
+        thecss.type = 'text/css';
+        thecss.rel = 'stylesheet';
+        document.getElementsByTagName('head').item(0).appendChild(thecss);
+        //$('head').append('<link rel="stylesheet" type="text/css" href="' + data.thecss + '">');
+
+        done = true;
+    }
+};