Enabling PDF JavaScript

Some PDF forms use JavaScript to improve the user experience. It can do a variety of things, such as change field colours, populating fields with options & running calculations as the user enters values.

FormVu makes an effort to emulate the frequently used features of the JavaScript for Acrobat API in the browser. For the majority of files you’ll find FormVu re-creates the functionality needed. It should be noted however, it is not able to emulate all methods and objects.

With the 2 different PDF Form formats (FDF & XFA), FormVu handles JavaScript differently in both cases.


JavaScript is enabled by default. This allows you to utilize some XFA specific features like dynamic reflow, allowing for the PDF to be expanded/reduced as required.


JavaScript is disabled by default. You can enable the setting either with FormViewerOptions or with a JVM flag.


FormViewerOptions formviewerOptions = new FormViewerOptions();

JVM Flag

The JVM flag can be set when run from command line:


or from Java:

System.setProperty("org.jpedal.pdf2html.enableFDFJavaScript", "true");

This will change the output so that you have two new files output:

  • FormvuFDF.js
  • EmbeddedScript.js

Where EmbeddedScript’s content contains the file specific custom JavaScript, this is then dynamically loaded into form.html via FormvuFDF.js.

We advise that users are careful with enabling JavaScript, a malicious PDF file could use JavaScript as a possible attack vector. In order to be safe, we suggest that you only convert with JavaScript enabled for PDF files that you trust.

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