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<!DOCTYPE html> <html> <body> <p>Click the button find out if the button has an onclick attribute specified.</p> <button onclick="myFunction()">Try it</button> <p id="demo"></p> <script> function myFunction() { var btn = document.getElementsByTagName("BUTTON")[0]; var x = btn.getAttributeNode("onclick").specified; document.getElementById("demo").innerHTML = x; } </script> </body> </html>