kekec_bbs/test.php

<?php
if(isset($_POST["save"])):
    echo "<script>alert('保存しました')</script>";

    $name = htmlspecialchars($_POST["name"], ENT_QUOTES); 
    $address = htmlspecialchars($_POST["address"], ENT_QUOTES); 
else:
?>
<form action="" method="post">
    <input type="text" name="name" value="<?= $name;?>">
    <input type="text" name="address" value="<?= $address;?>">
    <input type="submit" name="save" value="保存">
</form>
<?php
endif;
?>