JSFiddle - React, Tailwind, and code Playground
HTML
<span id="debug1"></span>
<span id="debug2"></span>JavaScript
var responseDoc = {"id":null,"category":"dog","price":"4321","name":"new product 123","sku":"1234","success":true};
document.getElementById("debug1").innerHTML=responseDoc;
var response = JSON.parse(responseDoc);
document.getElementById("debug2").innerHTML=response.category.toString();