Required library edition:
Required library file: dhtmlxlayout.js

returns cell's id

var id = dhxLayout.items[0].getId(); // will return "a"; [0] is item's index
  // or
var ids = new Array();
dhxLayout.forEachItem(function(item){
  ids[ids.length] = item.getId();
});
  // ids will contain ["a","b","c"...] depending on pattern