Capturing ctrl+z key combination in javascript

var btnUndo = $('#handPre')[0];

// https://stackoverflow.com/questions/16006583/capturing-ctrlz-key-combination-in-javascript
function KeyPress(e) {
      var evtobj = window.event? event : e
      if (evtobj.keyCode == 90 && evtobj.ctrlKey)
                btnUndo.click();
}

document.onkeydown = KeyPress;