The Selection.containsNode() method indicates whether a specified node is part of the selection.

node

The node that is being looked for in the selection.

partialContainment Optional

When true, containsNode() returns true when a part of the node is part of the selection. When false, containsNode() only returns true when the entire node is part of the selection. If not specified, the default value false is used.

Returns true if the given node is part of the selection, and false otherwise.

This snippet checks whether anything inside the body element is selected.

console.log(window.getSelection().containsNode(document.body, true));

In this example, a message appears when you select the secret word. It uses addEventListener() to check for selectionchange events.

HTML

<p>Can you find the secret word?</p>
<p>
  Hmm, where <span id="secret" style="color:transparent">SECRET</span> could it
  be?
</p>
<p id="win" hidden>You found it!</p>

JavaScript

const secret = document.getElementById("secret");
const win = document.getElementById("win");

// Listen for selection changes
document.addEventListener("selectionchange", () => {
  const selection = window.getSelection();
  const found = selection.containsNode(secret);

  win.toggleAttribute("hidden", !found);
});

Result

• Selection, the interface it belongs to.