diff --git a/doc/js2ts.php b/doc/js2ts.php
new file mode 100755
index 0000000000..41c75730bf
--- /dev/null
+++ b/doc/js2ts.php
@@ -0,0 +1,193 @@
+#!/usr/bin/env php
+<?php
+/**
+ * EGroupware - modify our old JS inheritance to TypeScript
+ *
+ * @link http://www.egroupware.org
+ * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
+ * @author Ralf Becker <rb@egroupware.org>
+ * @copyright 2020 by Ralf Becker <rb@egroupware.org>
+ */
+
+if (PHP_SAPI !== 'cli')	// security precaution: forbit calling as web-page
+{
+	die('<h1>fix_api.php must NOT be called as web-page --> exiting !!!</h1>');
+}
+
+// raw replacements
+$replace = array(
+	'/^app.classes.([a-z0-9_]+)(\s*=\s*AppJS.extend)\(.*^}\);/misU' =>
+		function($matches) {
+			return strtr($matches[0], [
+				'app.classes.'.$matches[1].$matches[2].'(' => 'class '.ucfirst($matches[1]).'App extends EgwApp',
+				"\n});" => "\n}\n\napp.classes.$matches[1] = ".ucfirst($matches[1])."App;"
+			]);
+		},
+	"/^\tappname:\s*'([^']+)',/m" => "\treadonly appname: '$1';",
+	"/^\t([^: ,;(]+):\s*([^()]+),/m" => "\t\$1: $2;",
+	"/^\t([^:\n]+):\s*function\s*\(.*this._super.(apply|call)\(/msU" =>
+		function($matches) {
+	        return str_replace('this._super',
+				$matches[1] === 'init' ? 'super' : 'super.'.$matches[1], $matches[0]);
+	    },
+	"/^\t([^:\n]+):\s*function\s*\(/m" => function($matches) {
+		return "\t".($matches[1] === 'init' ? 'constructor' : $matches[1]).'(';
+	},
+	"/^\t},$/m" => "\t}",
+	'/^ \* @version \$Id\$\n/m' => '',
+	'#^ \* @link http://www.egroupware.org#m' => ' * @link: https://www.egroupware.org',
+);
+
+/**
+ * Add boilerplate for app.js files after header
+ *
+ * @param $app
+ * @param $content
+ * @return string
+ */
+function app_js_add($app, $content)
+{
+	return preg_replace('#^(/\*\*.*\n\ \*/)#Us', <<<EOF
+$1
+
+/*egw:uses
+	/api/js/jsapi/egw_app.js
+ */
+
+import 'jquery';
+import 'jqueryui';
+import '../jsapi/egw_global';
+import '../etemplate/et2_types';
+
+import { EgwApp } from '../../api/js/jsapi/egw_app';
+EOF
+		, $content);
+}
+
+/**
+ * Convert JavaScript to TypeScript
+ *
+ * @param string $file filename
+ * @param boolean $dry_run =false true: only echo fixed file, not fix it
+ * @return boolean false on error
+ */
+function convert($file, $dry_run=false)
+{
+	global $prog, $replace;
+	if (basename($file) == $prog) return true;	// dont fix ourself ;-)
+
+	if (($content = $content_in = file_get_contents($file)) === false) return false;
+
+	$replace_callbacks = array_filter($replace, 'is_callable');
+	$replace_strings = array_filter($replace, 'is_string');
+
+	$content = preg_replace(array_keys($replace_strings), array_values($replace_strings),
+		preg_replace_callback_array($replace_callbacks, $content));
+
+	// add app.js spezific boilerplate
+	if (preg_match('#/([^/]+)/js/app(\.old)?\.js$#', realpath($file), $matches))
+	{
+		$content = app_js_add($matches[1], $content);
+	}
+
+	if ($content == $content_in) return true;	// nothing changed
+
+	if ($dry_run)
+	{
+		echo $content;
+	}
+	else
+	{
+		$ret = file_put_contents($new_file=preg_replace('/\.js$/', '.ts', $file), $content) === false ? -1 : 0;
+		//system('/usr/bin/php -l '.$file.'.new', $ret);
+		system('/usr/bin/diff -u '.$file.' '.$new_file);
+		return !$ret;
+	}
+
+	return true;
+}
+
+/**
+ * Loop recursive through directory and call fix_api for each php file
+ *
+ * @param string $dir
+ * @param boolean $dry_run =false true: only echo fixed file, not fix it
+ * @return boolean false on error
+ */
+function convert_recursive($dir, $dry_run=false)
+{
+	if (!is_dir($dir)) return false;
+
+	foreach(scandir($dir) as $file)
+	{
+		if ($file == '.' || $file == '..') continue;
+
+		if (is_dir($dir.'/'.$file))
+		{
+			convert_recursive($dir.'/'.$file, $dry_run);
+		}
+		elseif(substr($file,-3) == '.js')
+		{
+			echo "\r".str_repeat(' ',100)."\r".$dir.'/'.$file.': ';
+			convert($dir.'/'.$file, $dry_run);
+		}
+	}
+	echo "\r".str_repeat(' ',100)."\r";
+	return true;
+}
+
+/**
+ * Give usage
+ *
+ * @param string $error =null
+ */
+function usage($error=null)
+{
+	global $prog;
+	echo "Usage: $prog [-h|--help] [-d|--dry-run] file(s) or dir(s)\n\n";
+	if ($error) echo $error."\n\n";
+	exit($error ? 1 : 0);
+}
+
+$args = $_SERVER['argv'];
+$prog = basename(array_shift($args));
+
+if (!$args) usage();
+
+$dry_run = false;
+while(($arg = array_shift($args)) && $arg[0] == '-')
+{
+	switch($arg)
+	{
+		case '-h':
+		case '--help':
+			usage();
+			break;
+
+		case '-d':
+		case '--dry-run':
+			$dry_run = true;
+			break;
+
+		default:
+			if ($args)	// not last argument
+			{
+				usage("Unknown argument '$arg'!");
+			}
+			break 2;
+	}
+}
+
+do {
+	if (!file_exists($arg)) usage("Error: $arg not found!");
+
+	if (!is_dir($arg))
+	{
+		convert($arg, $dry_run);
+	}
+	else
+	{
+		convert_recursive($arg, $dry_run);
+	}
+}
+while(($arg = array_shift($args)));