js string转html节点

var str = "<h1>这是一个标题</h1>";
var parser = new DOMParser();
var doc = parser.parseFromString(str, "text/html");
var html = doc.body.firstChild;

const str = "<h1>这是一个标题</h1>";
const fragment = document.createDocumentFragment();
const range = document.createRange();
range.selectNode(document.body);
fragment.appendChild(range.createContextualFragment(str));
const html = fragment.firstChild;

const str = "<h1>这是一个标题</h1>";
const div = document.createElement("div");
div.innerHTML = str;
const html = div.firstChild;