JavaScript 获取网页表单 action 属性的方法

<!DOCTYPE html>
<html>
<body>
<form id="frm1" action="jb51.php">
First name: <input type="text" name="fname" value="Donald"><br>
Last name: <input type="text" name="lname" value="Duck"><br>
<input type="submit" value="Submit">
</form>
<p>The value of the action attribute is:
<script>
document.write(document.getElementById("frm1").action);
</script>
</p>
</body>
</html>

The value of the action attribute is:jb51.php