When you are making custom forms and you perform an update of a field using javascript or jQuery, the Forms inMotion application level listener is not made aware of that change in all browsers. The easiest way to let Forms inMotion know that you've changed field values programmatically is by forcing a call to the Forms_inMotion API. That one parameter call is shown below:
Step-by-step guide
This is called using the same integration as the Query API (Using the Query API) the Forms_inMotion function. That function will be injected into your form at load time.
Forms_inMotion("elementdataupdate");
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