HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>jQuery asterisk vs tilde attribute</title>
  <style>
    #samples span { display: block; margin: 6px 0; font-family: monospace; }
    #log { font-family: monospace; white-space: pre-line; margin-top: 12px; }
  </style>
</head>
<body>
  <div id="samples">
    <span class="btn primary">btn primary</span>
    <span class="primary-btn">primary-btn</span>
    <span class="toolbar">toolbar</span>
  </div>
  <div id="log"></div>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <script>
    var lines = [];
    $("#samples span").each(function() {
      var $el = $(this);
      lines.push(
        $el.attr("class") +
        " | *: " + $el.is("[class*='btn']") +
        " | ~: " + $el.is("[class~='btn']")
      );
    });
    $("#log").text(lines.join("\n"));
  </script>
</body>
</html>

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jQuery [class*='btn'] vs [class~='btn'] (Try It)