When the form is submitted, a new line is created. The data, which is the value of and fields, becomes the text content of the cells. A new instance is also created in the "users" сlass, where data is stored as the values of the object keys. Cell date attributes correspond to field id attributes and object instance keys. To change the text content in the line and the values of the keys in the corresponding instance, you need to click on the line, this will cause the appearance of a form that allows you to change the data. When you click the "Save changes" button, the new values are assigned to the text content of the cells of the line on which the event occurred and to the keys of the corresponding instance. By clicking on the "Delete" button, you can delete user data.
The program offers to delete only a row or a row and its corresponding object instance. You cannot delete just an instance. When you click on the "Cancel" button, the form disappears.