The hx-swap-oob attribute allows you to specify that some content in a response should be swapped into the DOM somewhere other than the target, that is “Out of Band”. This allows you to piggy back updates to other element updates on a response.
Consider the following response HTML:
<div>
...
</div>
<div id="alerts" hx-swap-oob="true">
Saved!
</div>
The first div will be swapped into the target the usual manner. The second div, however, will be swapped in as a replacement for the element with the id alerts, and will not end up in the target.
The value of the hx-swap-oob can be:
true
any valid hx-swap value
any valid hx-swap value, followed by a colon, followed by a CSS selector
If the value is true or outerHTML (which are equivalent) the element will be swapped inline.
If a swap value is given, that swap strategy will be used.
If a selector is given, all elements matched by that selector will be swapped. If not, the element with an ID matching the new content will be swapped.
Notes
hx-swap-oob is not inherited
Out of band elements must be in the top level of the response, and not children of the top level elements.
[HTMX Reference](https://htmx.org/attributes/hx-swap-oob/)