Get all Checkbox Values - (Doesn't matter Selected or Not)

I have one button "Download All" in this situation I want to get all the Checkbox values/ Records.

I have code to get Selected checkbox values - Rather than following I want All checkbox values should be there in "selectedFiels"

checkedSize = $("input:checkbox:checked.selectBox").length;
selectedFiels = $("input:checkbox:checked.selectBox");