Copy existing list item without serverside code

Hi All,

I have requirement to create sharepoint online(office 365) solution to create copy of list item.

In detail

I have button in ribbon, when user select any of the existing list item and click on that button it should pop up new list item with all fields populated from selected item i.e. it should be copy of the existing item.

Thing here is, it should not save the item while copying process, if user clicks on save then only it should save.

is this possible in sharepoint online? if yes please let me know any pointers to start.

Regards

Krishna