Utility function to sanitize simple inline HTML markup

src/pyj/utils.pyj

@@ -198,6 +198,25 @@ def conditional_timeout(elem_id, timeout, func):
             func.call(elem)
     window.setTimeout(ct_impl, timeout)
 
+
+def simple_markup(html):
+    html = (html or '').replace(/\u{ffff}/ug, '').replace(
+        /<\s*(\/?[a-zA-Z1-6]+)[^>]*>/g, def (match, tag):
+            tag = tag.toLowerCase()
+            is_closing = '/' if tag[0] is '/' else ''
+            if is_closing:
+                tag = tag[1:]
+            if simple_markup.allowed_tags.indexOf(tag) < 0:
+                tag = 'span'
+            return f'\uffff{is_closing}{tag}\uffff'
+    )
+    div = document.createElement('b')
+    div.textContent = html
+    html = div.innerHTML
+    return html.replace(/\u{ffff}(\/?[a-z1-6]+)\u{ffff}/ug, '<$1>')
+simple_markup.allowed_tags = v"'b|i|br|h1|h2|h3|h4|h5|h6|div|em|strong|span'.split('|')"
+
+
 if __name__ is '__main__':
     from pythonize import strings
     strings()