Creates an element from a string (without appending it to the document).
If the given string contains multiple elements, only the first one will be returned.

Use document.createElement() to create a new element.
Set its innerHTML to the string supplied as the argument.
Use ParentNode.firstElementChild to return the element version of the string.

代码片段

const createElement = str => {
  const el = document.createElement('div');
  el.innerHTML = str;
  return el.firstElementChild;
};

使用样例

const el = createElement(
  `<div class="container">
    <p>Hello!</p>
  </div>`
);
console.log(el.className); // 'container'