You can use the built-in JavaScript editor in Foxit PDF Editor (or an external JavaScript editor if you have specified one in File > Preferences > JavaScript) to create and edit all the JavaScripts in a PDF file. To open the JavaScript editor, choose Form > JavaScript > Edit All JavaScripts. In the JavaScript Editor dialog box, click Go to to jump to a specific line of code. After editing the JavaScripts, click OK to save it.
HTML User Manual Product
Foxit PDF Editor for Windows