JSFiddle - React, Tailwind, and code Playground

HTML

<ul data-bind="foreach: foo"><li data-bind="text: $data"></li></ul>
<ul data-bind="foreach: bar"><li data-bind="text: $data"></li></ul>
<pre data-bind="text: JSON.stringify(ko.toJS($root), null, 2)"></pre>

JavaScript

function ViewModel() {
    var self = this;
    
    self.foo = ko.observableArray(["fooA", "fooB"]);
    self.bar = ko.observableArray(["barA", "barB"]);
}

var vm = new ViewModel();

ko.applyBindings(vm);

vm.foo().unshift("fooZ");
vm.bar.unshift("barZ");