JSFiddle - React, Tailwind, and code Playground

HTML

<input data-bind="value: firstName">
<button data-bind="click: change">Change by code</button>
<button data-bind="click: test">Look</button>

JavaScript

var viewModel = {
    firstName: 'Fred',
    test: function () {
        alert(viewModel.firstName);
    },
    change: function () {
        viewModel.firstName = "new Value";
    }
};

ko.applyBindings(viewModel);