从php中的输入文本中获取值，而无需按Enter键

Hay I'm new to php and I have made php code like this :

<?php
    session_start();
    echo 'Hellow Hisoka';
?>
<form name="form" method="post">
    <div class="col-sm-3">
        <label class:>Nama :</label>
    </div>
    <div class="col-sm-9">
        <input type="text" name="nama_tamu" id='nama_tamu' class="form-control" placeholder="Nama Lengkap">
        <?php
            $myValue = $_POST['nama_tamu'];     
        ?>
    </div> 
    <br/><br/>
    <?php
        echo $myValue;
    ?>
</form>

When I want to show the echo message, I need to hit enter on my keyboard first in order to get the value of $_POST['nama_tamu'];. My question is can I get the value of nama_tamu input without pressing enter, or maybe without using POST or GET and then assign it to $myvalue?

For this purpose you should use .keyup function/event. Following are the snippet :

$(document).ready(function () {
  $("#nama_tamu").keyup(function(){
    $("#enterdata").html($("#nama_tamu").val());
     $.ajax({
        type: 'POST',
        url:  "getdata.php",
        data: "nama_tamu="+$("#nama_tamu").val(),
        success: function(res)
        {
            $("#outputdata").html(res);
        }
    });
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<?php
    session_start();
    echo 'Hellow Hisoka';
?>
<form name="form" method="post">
    <div class="col-sm-3">
        <label class:>Nama :</label>
    </div>
    <div class="col-sm-9">
        <input type="text" name="nama_tamu" id='nama_tamu' class="form-control" placeholder="Nama Lengkap">
        <?php
            $myValue = $_POST['nama_tamu'];     
        ?>
     <br> You press following character:<div id="enterdata"> </div>
    </div> 
    <br/><br/>
    <div id="outputdata"></div>
    <?php
        echo $myValue;
    ?>
</form>

Also create one file for the required output.

Now in getdata.php file

  echo $nama_tamu=$_POST['nama_tamu'];

</div>

Use keyup().

function check(id)
{
  document.getElementById("result").innerHTML = id;  
}

<input type="text" name="test" id="test" onkeyup="check(this.value);">
Your value: <span id="result"> </span>

$(document).ready(function() {
  $("#check").keyup(function(){
    alert($(this).val());
    });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" id="check" >

</div>

You will need to use Javascript. You can use the Jquery events :

<script>
    $( "#nama_tamu" ).keyup(function() {
        alert( $this.val() );// alerting the value of the input field
    });
</script>

Web development is all about communication. In this case, communication between two (2) parties, over the HTTP protocol:

• The Server - This party is responsible for serving pages.
• The Client - This party requests pages from the Server, and displays them to the user. In most cases, the client is a web browser.

Each side's programming, refers to code which runs at the specific machine, the server's or the client's.

You cannot get values without submitting for the user has not entered any yet. PHP is a server side language. To get values before submit and do certain actions with them you will need javascript (a client side programming language).

The simplest method to get a value is using the getElementById().

var something = document.getElementById('someid');

<input type="text" name="something" id="someid">

You can also use jQuery:

var something = $('#someid').val();

Conclusion

The simple answer to your question is: This is not possible.

Why not? I hear you asking. Because PHP doesn't know the values of your form before you send the form to your webserver.