appendHtml.js

function appendHtml(el, str) {
    var div = document.createElement('div');
    div.innerHTML = str;
    while (div.children.length > 0) {
      el.appendChild(div.children[0]);
    }
  }

  var test = "hi";

  var html = `<h1 id="title">Some ${test}</h1><span style="display:inline-block; width=100px;">Some arbitrary text</span>`;
  appendHtml(document.body, html); // "body" has two more children - h1 and span.
  document.body.appendChild(body);