diff --git a/lib/assets/libs/_html.js b/lib/assets/libs/_html.js
new file mode 100644
--- /dev/null
+++ b/lib/assets/libs/_html.js
@@ -0,0 +1,126 @@
+// creation of an HTML element
+var $module = (function($B){
+
+var _b_ = $B.builtins
+var $TagSumDict = $B.$TagSum.$dict
+
+function makeTagDict(tagName){
+    // return the dictionary for the class associated with tagName
+    var dict = {__class__:$B.$type,
+        __name__:tagName
+        }
+
+    dict.__init__ = function(){
+        var $ns=$B.args('__init__',1,{self:null},['self'],
+            arguments,{},'args','kw')
+        var self = $ns['self']
+        var args = $ns['args']
+        if(args.length==1){
+            var first=args[0]
+            if(_b_.isinstance(first,[_b_.str,_b_.int,_b_.float])){
+                self.elt.appendChild(document.createTextNode(_b_.str(first)))
+            } else if(first.__class__===$TagSumDict){
+                for(var i=0, _len_i = first.children.length; i < _len_i;i++){
+                    self.elt.appendChild(first.children[i].elt)
+                }
+            } else { // argument is another DOMNode instance
+                try{self.elt.appendChild(first.elt)}
+                catch(err){throw _b_.ValueError('wrong element '+first)}
+            }
+        }
+
+        // attributes
+        var items = _b_.list(_b_.dict.$dict.items($ns['kw']))
+        for(var i=0, _len_i = items.length; i < _len_i;i++){
+            // keyword arguments
+            var arg = items[i][0]
+            var value = items[i][1]
+            if(arg.toLowerCase().substr(0,2)==="on"){ 
+                // Event binding passed as argument "onclick", "onfocus"...
+                // Better use method bind of DOMNode objects
+                var js = '$B.DOMNodeDict.bind(self,"'
+                js += arg.toLowerCase().substr(2)+'",function(){eval("'+value+'")})'
+                eval(js)
+            }else if(arg.toLowerCase()=="style"){
+                $B.DOMNodeDict.set_style(self,value)
+            } else {
+                if(value!==false){
+                    // option.selected=false sets it to true :-)
+                    try{
+                        arg = arg.toLowerCase().replace('_','-')
+                        self.elt.setAttribute(arg,value)
+                    }catch(err){
+                        throw _b_.ValueError("can't set attribute "+arg)
+                    }
+                }
+            }
+        }
+    }
+
+    dict.__mro__ = [dict,$B.DOMNodeDict,$B.builtins.object.$dict]
+
+    dict.__new__ = function(cls){
+        // __new__ must be defined explicitely : it returns an instance of
+        // DOMNode for the specified tagName
+        var res = $B.DOMNode(document.createElement(tagName))
+        res.__class__ = cls.$dict
+        return res
+    }
+
+    return dict
+}
+
+
+// the classes used for tag sums, $TagSum and $TagSumClass 
+// are defined in py_dom.js
+
+function makeFactory(tagName){
+    var factory = function(){
+        var res = $B.DOMNode(document.createElement(tagName))
+        res.__class__ = dicts[tagName]
+        // apply __init__
+        var args = [res].concat(Array.prototype.slice.call(arguments))
+        dicts[tagName].__init__.apply(null,args)
+        return res
+    }
+    factory.__class__=$B.$factory
+    factory.$dict = dicts[tagName]
+    return factory
+}
+
+// All HTML 4, 5.x extracted from
+// https://w3c.github.io/elements-of-html/
+// HTML4.01 tags
+var $tags = ['A','ABBR','ACRONYM','ADDRESS','APPLET','AREA','B','BASE',
+            'BASEFONT','BDO','BIG','BLOCKQUOTE','BODY','BR','BUTTON',
+            'CAPTION','CENTER','CITE','CODE','COL','COLGROUP','DD',
+            'DEL','DFN','DIR','DIV','DL','DT','EM','FIELDSET','FONT',
+            'FORM','FRAME','FRAMESET','H1','H2','H3','H4','H5','H6',
+            'HEAD','HR','HTML','I','IFRAME','IMG','INPUT','INS',
+            'ISINDEX','KBD','LABEL','LEGEND','LI','LINK','MAP','MENU',
+            'META','NOFRAMES','NOSCRIPT','OBJECT','OL','OPTGROUP',
+            'OPTION','P','PARAM','PRE','Q','S','SAMP','SCRIPT','SELECT',
+            'SMALL','SPAN','STRIKE','STRONG','STYLE','SUB','SUP',
+            'TABLE','TBODY','TD','TEXTAREA','TFOOT','TH','THEAD',
+            'TITLE','TR','TT','U','UL','VAR',
+            // HTML5 tags
+            'ARTICLE','ASIDE','AUDIO','BDI','CANVAS','COMMAND','DATA',
+            'DATALIST','EMBED','FIGCAPTION','FIGURE','FOOTER','HEADER',
+            'KEYGEN','MAIN','MARK','MATH','METER','NAV','OUTPUT',
+            'PROGRESS','RB','RP','RT','RTC','RUBY','SECTION','SOURCE',
+            'TEMPLATE','TIME','TRACK','VIDEO','WBR',
+             // HTML5.1 tags
+            'DETAILS','DIALOG','MENUITEM','PICTURE','SUMMARY']
+
+// create classes
+var obj = new Object()
+var dicts = {}
+for(var i=0, _len_i = $tags.length; i < _len_i;i++){
+    var tag = $tags[i]
+    dicts[tag] = makeTagDict(tag)
+    obj[tag] = makeFactory(tag)
+    dicts[tag].$factory = obj[tag]
+}
+$B.tag_classes = dicts
+return obj
+})(__BRYTHON__)