The callback for status bar update. Called when status bar bind or update function, or status bar check changed in context menu. The update related operations can realize in it. Users also should call onUpdate when current item need update. The default operations in super is update current item by visible.

var instance = new GC.Spread.Sheets.StatusBar.StatusItem(name, options);
var value; // Type: any
value = instance.onUpdate();

function onUpdate() : any;

let StatusItem = GC.Spread.Sheets.StatusBar.StatusItem;
function LabelItem (name, options) {
  StatusItem.call(this, name, options);
}
LabelItem.prototype = new StatusItem();
LabelItem.prototype.onUpdate = function () {
  StatusItem.prototype.onUpdate.call(this);
  // update item.