SPO Announcements knockoutjs sort observable array.

Question

I am trying to show new announcements on top & drop off expired announcements from UI using knockoutjs. Being a newbie to knockout, i'm stuck here and unable to move further. here's a piece of code which needs some correction. Appreciate any pointers to resolve this issue. and on the UI, I am using data bind="foreach: items, as: 'item'" to ul element.

function ItemViewModel(params)
{
this.text = ko.observable(params.title);
//this.id = ko.observable(params.id);
this.link = ko.observable(params.path);
this.cssClass = ko.observable("");
}
function viewModel(params)
{
var self = this;
this.isLoading = ko.observable(true).extend({ throttle: 250 });
this.studio = ko.observable(params.studio || "");
this.maxItems = ko.observable(params.maxItems || 8);
this.items = ko.observableArray([]);
this.dialogId = ko.observable('AnnouncementsModal');
this.addItem = function (item, e)
{
navigationService.navigateTo('/Announcements/NewForm.aspx', true);
e.preventDefault(); };
this.canAddItem = ko.computed(function()
{
var isLeader = contextService.isLeader();
var isContributor = contextService.isContributor();
return isLeader || isContributor; }, this);
this.hasNoItems = ko.computed(function()
{
var items = self.items();
return items.length === 0;
}, this).extend({ throttle: 250 });
this.searchTerm = ko.computed(function ()
{
var studio = contextService.studio();
if (studio)
{
return studio;
}
return self.studio();
});
ko.computed(function ()
{
var maxItems = self.maxItems();
var term = self.searchTerm();
if (term == null || term === "")
return null;
self.isLoading(true);
console.log('announcements-webpart/vm.js: data-service load...');
dataService.studios.announcements(term, maxItems) .done(function (result)
{
console.log('announcements-webpart/vm.js: data-service load completed.');
self.isLoading(false);
self.items.removeAll();
if (result.items)
{
for (var i = 0; i < result.items.length; i++)
{
if (i >= maxItems) return;
var item = new ItemViewModel(result.items[i]);
self.items.push(item);
}
}
}); return null;
}, this).extend({ deferred: true });
}
viewModel.prototype.dispose = function () { };
return viewModel; })();