“An invalid or illegal string was specified” Exception in GWT

While work­ing with can­vas (draw­ing stuff on it) in GWT, sud­denly and in a seem­ingly unpre­dictable man­ner I got fol­low­ing error mes­sage now and then from within the GWT frame­work code:

com.google.gwt.core.client.JavaScriptException: (NS_ERROR_DOM_SYNTAX_ERR): An invalid or illegal string was specified;

Again, GWT tricked me into think­ing I am writ­ing Java code and made me for­get about that it is going to be com­piled into Javascript. And because of the lat­ter, a divi­sion by zero does not throw an Devi­sion­ByZe­roEx­cep­tion, no, it returns NaN even for native data types (there is no dif­fer­en­ti­a­tion between dou­ble and Dou­ble in Javascript — there is only the object-version of dou­ble, which can be of value Double.NaN).

But also GWT was not pre­pared to han­dle Double.NaN. When call­ing canvas.getContext().drawImage(image,x,y) and one of x and y or both were Double.NaN I got the error mes­sage shown above. If you got the same… you know what to do now: check all devi­sions in your code for poten­tial devi­sions by zero!!

How to Make Jquerymenu for Drupal Keep its State on Page Reload

While set­ting up the web­site for my new project “Glo­cal” www.glocal-project.eu), I came across the prob­lem of find­ing a proper menu mod­ule. Some­thing easy to use, sta­ble and effi­cient in the same time for the com­plex intranet struc­ture (there­fore, sorry, but you will not be able to see my solu­tion there unless you are a project mem­ber). Some­thing with a high usabil­ity in the end. Active­menu is still quite buggy and DHTML Menue requires a dou­ble click to actu­ally open a page — unbear­able in a non-doulbe-click envi­ron­ment like the Inter­net — who is sup­posed to guess, that this menu requires a dou­ble click?? Leav­ing me with JQuery­menu.

First impres­sion: per­fect! Open and close branches by click­ing (+) or (-) — view page by click­ing menu item label. Even the few styling issues could be fixed eas­ily by using CSS. But as soon, as some­one clicks a label, the menu col­lapses to its default sta­tus. It does not remem­ber its last sta­tus after load­ing a dif­fer­ent page with the same menu.

Is this it? All mod­ule have crit­i­cal down­sides like this? I was quite dis­ap­pointed!

But I taught JQuery­menu to remember!

As it is quite some code, I will not post it here directly, but added it to the tracker page for this “fea­ture request” or you can down­load the two updated files (jquerymenu.js and jquerymenu.module) here and replace the once in your /sites/all/modules/jquerymenu folder.

But please be care­ful, it should be con­sid­ered an alpha ver­sion, there are quite some weak­nesses (see tracker page). Any feed­back or sug­ges­tions are very wel­come!