Only the contents of onblur, onchange, onclick, ondblclick, ondrag, ondrop, onfocus, onkeydown, onkeypress, onkeyup, onload, onmousedown, onmousemove, onmouseout, onmouseover, onmouseup, onreset, onselect, onsubmit and onunload are highlighted as JavaScript.

The rest of the properties which Netbeans autocompletes is not:

onabort, onafterprint, onautocomplete, onautocompleteerror, onbeforeprint, onbeforeunload, oncancel, oncanplay, oncanplaythrough, onclose, oncontextmenu, oncuechange, ondragend, ondragenter, ondragexit, ondragleave, ondragover, ondragstart, ondurationchange, onemptied, onended, onerror, onhashchange, oninput, oninvalid, onlanguagechange, onloadeddata, onloadedmetadata, onloadstart, onmessage, onmouseenter, onmousewheel, onoffline, ononline, onpagehide, onpageshow, onpause, onplay, onplaying, onpopstate, onprogress, onratechange, onresize, onscroll, onseeked, onseeking, onshow, onstalled, onstorage, onsuspend, ontimeupdate, ontoggle, onvolumechange, onwaiting