In form I have button, i want display field "Price" after button "Save" click, it's possible ? Or can be solution to add to field HTML atribute "readonly".
In your form, enable option "Generate HTML for all fields" (check the image below):
It will generate html for all fields, even for hidden ones.
Add field price
to the form and hide id by paragraph hide formulas according to your requirements.
When you have saved your form, add a flag to your document, that turns the hide formula for price
field to false, and invoke the command:
@Command( [RefreshHideFormulas] );
It will make your price
field visible.