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<!DOCTYPE html> <html> <body> <p>This example uses the addEventListener() method to attach a "keyup" event to an input element.</p> <p>Press a key inside the text field and release it to set a red background color.</p> Enter your name: <input type="text" id="fname"> <script> document.getElementById("fname").addEventListener("keyup", myFunction); function myFunction() { var x = document.getElementById("fname"); x.value = x.value.toUpperCase(); } </script> </body> </html>