JSFiddle - React, Tailwind, and code Playground

HTML

<div class="fields">
<input type="checkbox" id="chkField"/>
<input type="text" size="20" id="txtName" disabled="true"/>
</div>

CSS

.fields {
   margin-top: 10px;
   margin-left: 10px;
}

JavaScript

var c = document.getElementById("chkField");
var txt = document.getElementById("txtName");

if(c !== undefined) {
    c.onclick = function(event) {
        txt.disabled = !this.checked;
    }
}