To inspect dart object, open console, select cj-grid, we can find dart object is export to javascript and inspectable in javascript console
          var grid= document.querySelector('cj-grid').grid; //this is SlickGrid object
          var column = grid.columns.$index(0,0);  // this is dart Column Object
          column.toString$0()  // call toString function in dart object that produce json string...
          //"{name: input, resizable: false, sortable: false, minWidth: 30, rere....}"

        
Panel 1, bind surface
Panel 2