JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" id="cb" />
<label for="cb">label for checkbox</label>
<input type="text" id="txt" style="display: none;" />

JavaScript

var checkbox = $('#cb');
var textfield = $('#txt');

checkbox.click(function() {
    if (checkbox.is(':checked')) {
        textfield.show();
    }
    else
    {
        textfield.hide();
    }
});