W3School TIY Editor
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<!DOCTYPE html> <html> <body> <form action="/demo/html/action_page.php" method="get"> Pick a number between 2 and 5: <input type="number" id="myInput" name="quantity" min="2" max="5" required> <input type="submit" value="Submit"> </form> <p>如果您提交表单的数字小于 2 或大于 5，将出现警告消息。</p> <p><b>注释：</b>Internet Explorer 9 及更早版本或 Safari 不支持 oninvalid 事件。</p> <script> document.getElementById("myInput").addEventListener("invalid", myFunction); function myFunction() { alert("You must pick a number between 2 and 5. You chose: " + this.value); } </script> </body> </html>