How to add a row with drop down in cells?

ADov

var button = '<button type="button" id="guideContainer-rootPanel-panel-guidebutton___widget">Add</button>';
var idButton = $("#guideContainer-rootPanel-panel-guidebutton___widget");
idButton.replaceWith(button);

$("#guideContainer-rootPanel-panel-guidebutton___widget").on('click',function(){
//debugger;
detailsTableDailyExcess.row.add( {
"institution": "",
"region": "",
"branch": "",
"rgm": "",
"crm": "",
"ID": "",
} ).draw();
});

//I am trying to add drop down to "institution","region" and "branch". Right now I am able to add an empty row when I click the button