JSFiddle - React, Tailwind, and code Playground

HTML

<h3>Diagnosis Codes<input type="button" value="Add" data-bind="click:AddDiagnosisCode"/></h3>
<div data-bind="foreach:DiagnosisCodes">
    <div><input type="text" data-bind="value:$data, hasFocus: true">
    </div>
</div>

JavaScript

var DiagnosisViewModel = function()
{
    var self = this;

    self.DiagnosisCodes = ko.observableArray();
    
    self.AddDiagnosisCode = function()
    {
        self.DiagnosisCodes.push("");
    }
}    
ko.applyBindings(new DiagnosisViewModel());