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....}"
To use custom JGrid, must specify height of element