JSFiddle - React, Tailwind, and code Playground

by kougiland

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/knockout/2.1.0/knockout-min.js"></script>
<textarea data-bind="value: comment, valueUpdate: 'afterkeydown', disable: count() <= 0"></textarea>

<br/><br/>
<span data-bind="text: count"></span> characters

JavaScript

var viewModel = {
    comment : ko.observable(""),
};
viewModel.count = ko.computed(function(){
        var countNum = 20 - viewModel.comment().length;
        return countNum;
    });    
ko.applyBindings(viewModel);