JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/knockout/knockout-3.0.0.js"></script>
<table>
                    <tr>
                        <td>Primary Classification</td>
                        <td>Manufacturer Name</td>
                        <td>Description</td>
                        <td>Size</td>
                    </tr>
                    <tr>
                        <td>
                            <input class="itemText" type="text" data-bind=" value: primaryClassification, disable: false" />
                        </td>
                        <td>
                            <input class="itemText" type="text" data-bind="value: manufacturerName, disable: false" />
                        </td>
                        <td>
                            <input class="itemText" type="text" data-bind="value: description, disable: false" />
                        </td>
                        <td>
                            <input class="itemText" type="text" data-bind="value: size, disable: false" />
                        </td>
                    </tr>
</table>
                <div>Long Description:</div>
                <input class="itemText" type="text" data-bind="value: longDescription, disable: true" />

JavaScript

function AppViewModel() {
        var self = this;
        self.primaryClassification = ko.observable('');        
        self.manufacturerName = ko.observable('');
        self.description = ko.observable('');      
        self.size = ko.observable('');
        self.longDescription = ko.observable();
        self.primaryClassification.subscribe(function () {     
            updateLongDescription(self);
        });  
        self.manufacturerName.subscribe(function () {     
            updateLongDescription(self);
        });
        self.description.subscribe(function () {     
            updateLongDescription(self);
        });
        self.size.subscribe(function () {     
            updateLongDescription(self);
        });
    }

    function updateLongDescription(self){        
            var value = self.primaryClassification() + self.manufacturerName() 
            value += self.description() + self.size();            
            self.longDescription(value);     
    }

    ko.applyBindings(new AppViewModel());