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<!DOCTYPE html> <html> <body> Cats: <input name="animal" type="checkbox" value="Cats"> Dogs: <input name="animal" type="checkbox" value="Dogs"> <p>Click the button to find out how many elements there are in the document that have a name attribute with the value "animal".</p> <button onclick="myFunction()">Try it</button> <p id="demo"></p> <script> function myFunction() { var x = document.getElementsByName("animal").length; document.getElementById("demo").innerHTML = x; } </script> </body> </html>