JSFiddle - React, Tailwind, and code Playground
HTML
<select data-bind="value:value">
<option>Choose...</option>
<!-- ko foreach:items -->
<option data-bind="text:key, attr:{value:value}"></option>
<!-- /ko -->
</select>
JavaScript
var viewmodel = {
items:[{key:"test", value:1},{key:"test2", value:2}],
value: ko.observable(1)
};
ko.applyBindings(viewmodel);