how to add id in jquery to an element code example

Example 1: how to add id in jquery

$( "p" ).add( "div" ).addClass( "widget" );
var pdiv = $( "p" ).add( "div" );

Example 2: how to add id in jquery

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>append demo</title>
  <style>
  p {
    background: yellow;
  }
  </style>
  <script src="https://code.jquery.com/jquery-3.5.0.js"></script>
</head>
<body>
 
<strong>Hello world!!!</strong>
<p>I would like to say: </p>
 
<script>
$( "p" ).append( $( "strong" ) );
</script>
 
</body>
</html>

Example 3: how to add id in jquery

var pdiv = $( "p" );
pdiv.add( "div" ); // WRONG, pdiv will not change