Please see the sample here: https://github.com/episerver/EPiServer.Forms.Samples/blob/master/ClientResources/ViewMode/EPiServerFormsSamples.js
the method showSummarizedText will show jquery dialog when submit form instead of alert. You can overide that method to customize the message.
Is it possible to customize the summary alert popup in Forms when selecting "Show a summary confirmation message after submission"?
For example I would like to remove/hide some specific form elements from the summary popup.