小编Her*_*191的帖子

我到处搜索,我无法想出解决方案.每次用户点击"提交"(该部分有效)时,我都会尝试使此代码显示图表.问题出在用户点击提交多次一次.它多次显示图表.如何删除最后一个图表并使用新图表进行更新？

function doGet() {
  var uiApp = UiApp.createApplication().setTitle("some title");

  var grid = uiApp.createGrid(3, 2);
  grid.setWidget(0, 0, uiApp.createLabel('Lablel 1'));
  grid.setWidget(1, 0, uiApp.createLabel('Lablel 2'));

  var panel = uiApp.createVerticalPanel();

  panel.add(grid);

  var button = uiApp.createButton('submit');
  var handler = uiApp.createServerHandler('b');
  handler.addCallbackElement(grid);
  button.addClickHandler(handler);

  panel.add(button);
  uiApp.add(panel);

  return uiApp;
 }

function b(e) {
  var app = UiApp.getActiveApplication();

  //gets all my chart data
  var chart = getchartdata()

  //Add chart
  app.add(chart)

  var uiApp = UiApp.getActiveApplication();
  uiApp.close();

  return uiApp;
}