当点击按钮时，我如何使返回的消息出现在没有其他代码的同一页面上 - When clicked on button, how can i make the returned message appear on the same page without other code?

When clicked on button, how can i make the returned message appear on the same page without other code?

代码:

<!DOCTYPE html>
<html>
<head>
<title>Greeting Service!</title>
</head>
<body>
<center>
<form method="post" action="">
<h1>What's Your Name?</h1>
<input type="text" name="name" placeholder="Name Here" />
<h4>Greet me in:
<select name="language">
<option value="option1">English</option>
<option value="option2">Chinese</option>
<option value="option3">French</option>
</select>
</h4>
<input type="submit" value="Greet Me!" />
<?php
if (isset($_POST['language'])) {
$language = $_POST['language'];
switch ($_POST['language']) {
case "option1":
$result = "Hello, {$_POST['name']}!"; 
break;
case "option2":
$result = "你好, {$_POST['name']}!"; 
break;
case "option3":
$result = "Bonjour, {$_POST['name']}!"; 
break;
}
}
?>
</form>
</center>
</body>
</html>

我不知道如何使问候本身出现在完全相同的页面上，但没有文本框输入名称，选择选项和提交按钮。因为目前当我输入一个名字，并选择例如用英文问候这个名字时，它会在提交按钮旁边发出回声。我希望它在同一页上回声，但不显示页面的其余部分。我能做到吗?

试试这个

    <!DOCTYPE html>
    <html>
    <head>
    <title>Greeting Service!</title>
    </head>
    <body>
 <?php
    if (isset($_POST['language'])) {
    $language = $_POST['language'];
    $result='';
    switch ($_POST['language']) {
    case "option1":
    $result = "Hello, {$_POST['name']}!"; 
    break;
    case "option2":
    $result = "你好, {$_POST['name']}!"; 
    break;
    case "option3":
    $result = "Bonjour, {$_POST['name']}!"; 
    break;
    }
    echo $result;
    }
else{
    ?>
    <center>
    <form method="post" action="">
    <h1>What's Your Name?</h1>
    <input type="text" name="name" placeholder="Name Here" />
    <h4>Greet me in:
    <select name="language">
    <option value="option1">English</option>
    <option value="option2">Chinese</option>
    <option value="option3">French</option>
    </select>
    </h4>
    <input type="submit" value="Greet Me!" />
    </form>
    </center>
<?php }?>
    </body>
    </html>