diff --git a/js/util.js b/js/util.js
deleted file mode 100644
index 99fa91a..0000000
--- a/js/util.js
+++ /dev/null
@@ -1,79 +0,0 @@
-/* Copyright 2010-2019 Will Scullin <scullin@scullinsteel.com>
- *
- * Permission to use, copy, modify, distribute, and sell this software and its
- * documentation for any purpose is hereby granted without fee, provided that
- * the above copyright notice appear in all copies and that both that
- * copyright notice and this permission notice appear in supporting
- * documentation.  No representations are made about the suitability of this
- * software for any purpose.  It is provided "as is" without express or
- * implied warranty.
- */
-
-var hex_digits = '0123456789ABCDEF';
-var bin_digits = '01';
-
-export function allocMem(size) {
-    var result;
-    if (window.Uint8Array) {
-        result = new Uint8Array(size);
-    } else {
-        result = new Array(size);
-    }
-    return result;
-}
-
-export function allocMemPages(pages) {
-    return allocMem(pages * 0x100);
-}
-
-export function debug(msg) {
-    /*eslint no-console: 0 */
-    if (typeof(console) != 'undefined' && 'log' in console) {
-        console.log(msg);
-    } else if (typeof(environment) == 'object') { // rhino shell
-        print(msg);
-    }
-}
-
-export function toHex(v, n) {
-    if (!n) {
-        n = v < 256 ? 2 : 4;
-    }
-    var result = '';
-    for (var idx = 0; idx < n; idx++) {
-        result = hex_digits[v & 0x0f] + result;
-        v >>= 4;
-    }
-    return result;
-}
-
-export function toBinary(v) {
-    var result = '';
-    for (var idx = 0; idx < 8; idx++) {
-        result = bin_digits[v & 0x01] + result;
-        v >>= 1;
-    }
-    return result;
-}
-
-// From http://www.netlobo.com/url_query_string_javascript.html
-export function gup( name )
-{
-    name = name.replace(/[[]/,'\\[').replace(/[\]]/,'\\]');
-    var regexS = '[\\?&]'+name+'=([^&#]*)';
-    var regex = new RegExp( regexS );
-    var results = regex.exec( window.location.href );
-    if( !results )
-        return '';
-    else
-        return results[1];
-}
-
-export function hup() {
-    var regex = new RegExp('#(.*)');
-    var results = regex.exec(window.location.hash);
-    if ( !results )
-        return '';
-    else
-        return decodeURIComponent(results[1]);
-}
diff --git a/js/util.ts b/js/util.ts
new file mode 100644
index 0000000..01b7dbc
--- /dev/null
+++ b/js/util.ts
@@ -0,0 +1,67 @@
+/* Copyright 2010-2023 Will Scullin <scullin@scullinsteel.com>
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation.  No representations are made about the suitability of this
+ * software for any purpose.  It is provided "as is" without express or
+ * implied warranty.
+ */
+
+import { byte, word } from "./types";
+
+var hex_digits = "0123456789ABCDEF";
+var bin_digits = "01";
+
+export function allocMem(size: word) {
+  var result;
+  if (window.Uint8Array) {
+    result = new Uint8Array(size);
+  } else {
+    result = new Array(size);
+  }
+  return result;
+}
+
+export function allocMemPages(pages: byte) {
+  return allocMem(pages * 0x100);
+}
+
+export function debug(...msg: unknown[]) {
+  /*eslint no-console: 0 */
+  console.log(...msg);
+}
+
+export function toHex(v: byte, n?: 2 | 4) {
+  if (!n) {
+    n = v < 256 ? 2 : 4;
+  }
+  var result = "";
+  for (var idx = 0; idx < n; idx++) {
+    result = hex_digits[v & 0x0f] + result;
+    v >>= 4;
+  }
+  return result;
+}
+
+export function toBinary(v: byte) {
+  var result = "";
+  for (var idx = 0; idx < 8; idx++) {
+    result = bin_digits[v & 0x01] + result;
+    v >>= 1;
+  }
+  return result;
+}
+
+export function gup(name: string) {
+  const params = new URLSearchParams(window.location.search);
+  return params.get(name);
+}
+
+export function hup() {
+  var regex = new RegExp("#(.*)");
+  var results = regex.exec(window.location.hash);
+  if (!results) return "";
+  else return decodeURIComponent(results[1]);
+}