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<!DOCTYPE html> <html> <head> <style> .example { border: 1px solid black; margin: 5px; } </style> </head> <body> <div class="example"> A div with class="example" </div> <div class="example"> Another div with class="example" </div> <p>This is a p element with class="example".</p> <p>This is a <span class="example">span</span> element with class="example" inside another p element.</p> <p>Click the button to change the background color of all elements with class="example".</p> <button class="example" onclick="myFunction()">Try it</button> <p><strong>Note:</strong> The getElementsByClassName() method is not supported in Internet Explorer 8 and earlier versions.</p> <script> function myFunction() { var x = document.getElementsByClassName("example"); var i; for (i = 0; i < x.length; i++) { x[i].style.backgroundColor = "red"; } } </script> </body> </html>