How to do regular expression replacement with jQuery?

Question

JavaScript

Hello.
There is a markup How to turn it into a regular? In my case, it doesn't quite work. Thank you.
<b id="idname">some_content</b>

<b id="idname">some_content2</b>


$("#elementID").html("another string");

Answer 1

Get the content from the first element, connect to the desired content, and paste it into the second element.
Why is this regular?

Answer 2

https://jsfiddle.net/hxhj7h86/2/
Regular is definitely not needed