[Pas2js] htmlwidget in pas2j 2.2.0: pas.JS.isUndefined is not a function

Michael Van Canneyt michael at freepascal.org
Mon Aug 29 14:11:51 CEST 2022

On Mon, 29 Aug 2022, Luca Olivetti wrote:

> As per the subject, I'm using pas2js 2.2.0 with fpc 3.2.2 and lazarus 2.2.2.
> Since I had problems with Pas2JS_Widget, I'm now back to the basics following 
> this article:
> https://www.freepascal.org/~michael/articles/pas2js1/pas2js1.pdf
> and while the first method (page 12, plain javascript classes) works, if I 
> try to use the second one (using the httpwidget unit, not the webwidget one 
> as the article says) I get this error in firefox:
> Uncaught TypeError: pas.JS.isUndefined is not a function
>    EventEntry webwidget.pas:2640
>    cb rtl.js:256
>    cb rtl.js:256
>    HookupEvent webwidget.pas:2665
>    AddEvent webwidget.pas:2690
>    SetHTMLEvent webwidget.pas:2477
>    DoRun login.lpr:27
>    Run custapp.pas:206
>    $main login.lpr:62
>    run rtl.js:141
>    <anonymous> login.html:51
> webwidget.pas:2640:10

very strange, it works here. if I look in the Javascript, I can see the

Can you look in the generated .js file, you should see something like:

   this.isUndefined = function (v) {
     return v == undefined;
   this.isDefined = function (v) {
     return !(v == undefined);

Are you using optimizations ? If so, please try adding -O- in the custom
options of the compiler.


More information about the Pas2js mailing list