Closed

<input type="text" id="input-field"> <div id="error-message" style="display: none;">This is not a valid membership number./div> <script> const inputField = document.getElementById(“input-field"); const errorMessage = document.getElementById(“error-message"); inputField.addEventListener("blur", function () { if (this.value.length !== 8) { errorMessage.style.display = "block"; } else { errorMessage.style.display = “none”; } }); </script>