JSFiddle - React, Tailwind, and code Playground

JavaScript

var str = '<!DOCTYPE html><html><div id="d1"><p>foo</p></div></html>';

var htmlWrapper = document.createElement('html');
htmlWrapper.innerHTML = str;
var pNodes = htmlWrapper.getElementsByTagName('p');

document.body.innerHTML = pNodes[0].innerText || pNodes[0].textContent;