@giri-zano This is not responsive to the question posed. I, like @artpuryear, have found the explanations of what exactly a date/time field in a Wix collection is to be less than transparently obvious. People who are accustomed to working with JavaScript point to the w3schools.com website for an answer to a question about the behavior of Wix’s adaptation of JavaScript, but that does not explain what one has to do specifically to do something that should be simple to actually happen.
The new Date() object in JavaScript contains the date and time as measured in milliseconds since 1970, and through some skulduggery, it ends up being rendered as a human-recognizable date and time if the right code is used. That does not tell us how Wix uses that technology to create what it calls a date/time field, nor does it tell us how we can create a value that can be saved to a date/time field and end up with something that looks like a date and time value.
For instance, I have used new Date() and saved it to a d/t field, but all that is saved is a date with no time component at all. I have used new Date().getTime(), which converts the mystical soup that JavaScript calls a date value into the number of milliseconds since 1970 and tried to save that, and what I end up with is a very large number in my collection with an indication of an error as well.
It would be nice if someone would just produce some straightforward code that takes a new Date() object, applies the secret sauce that is necessary to make it incorporate a time element that Wix understands, save it to a d/t field in Wix, and have it end up looking like a date and time when looking at the collection in the Wix editor. That should not be so hard to get, but so far no one has been responsive to this very fundamental question.