This article describes a way to extend and override the standard behavior of ADF client side JavaScript libraries. In this particular case we needed to learn about the client side validation errors in order to feed our expertise manager: when the user submits the form, client side validations are performed and when errors are found, these are presented to the end user. We would like to intercept this standard flow and also listen in to the list of validation error messages that will be shown to the end user.

A little debugging using Firefox quickly made it clear that the submitForm() method is invoked when a command button is activated and that it in turn (indirectly) makes use of the function processValidators() on the AdfHtmlPage object. This function will return true or false, depending on whether any validation error messages were produced by the collected validators that fire.

We can extend this function – without having to change any of the source code. The standard JavaScript way of overriding a method on an object is through the prototype of that object – and a reference to the original function.

The steps are:

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