Solution, try: 1. UniFormCreate -> procedure TUniForm2.UniFormCreate(Sender: TObject); begin inherited; UniButton3.JSInterface.JSAssign('_createorder', [1]); UniContainerPanel2.JSInterface.JSAssign('_createorder', [2]); UniButton1.JSInterface.JSAssign('_createorder', [3]); UniButton2.JSInterface.JSAssign('_createorder', [4]); end; 2. UniContainerPanel1.ClientEvents.ExtEvents -> function boxready(sender, width, height, eOpts) { (function() { var arr = []