Webix jet datbabase Update logic

Hi
i’m try to write a test app within Jet … now i should write the DB Update logic; in the examples that i saw, i find the DB read logic, that is in models.records.js. Question : for the DB Update(Write/update/delete), which standard is better to follow ? a .js like record.js that receive form values ? how can “structure” the DB Update logic … whre can i find an example .
i was thinging to put in my formjs a sendJSONData(values) … but where to put sendJSONData function ?
thanks in advance … any idea / suggestion wil be appreciated