javascript 需要输入更改输入边框

Question

如果用户在发布后将输入留空，我将尝试更改边框

好吧，我试过了:

<script>
   function required (id) {
       document.getElementById(id).style.border = "#FF0000 5px inset";
   }
</script>
<form method="post">
<input type='text' id='req' name='t'>
</form>
<?
if ($_POST)
   if (isset($_POST['t']))
        echo "u've done";
   else
        echo "<script>required('req');</script>";
?>

Answer 1

将您的 PHP 代码更改为以下内容:

<?php // <- no short tag
if ($_POST) { // <-- add brackets
   if (isset($_POST['t']))
        echo "u've done";
   else
        echo "<script>required('req');</script>";
} // <-- add brackets
?>