Range: surroundContents() method

The Range.surroundContents() method moves content of the Range into a new node, placing the new node at the start of the specified range.

This method is nearly equivalent to newNode.appendChild(range.extractContents()); range.insertNode(newNode). After surrounding, the boundary points of the range include newNode.

An exception will be thrown, however, if the Range splits a non-Text node with only one of its boundary points. That is, unlike the alternative above, if there are partially selected nodes, they will not be cloned and instead the operation will fail.

surroundContents(newParent)

<span class="header-text">Put this in a headline</span>

const range = document.createRange();
const newParent = document.createElement("h1");

range.selectNode(document.querySelector(".header-text"));
range.surroundContents(newParent);