JQuery and PHP pressing enter to process

I have the following two files request.php and response.php. I used to send the request using a button

    <input type="button" value="Request message" onclick="post()"/>

but now I and considering using just the "Enter"(13) key.

The code works, however it shows the result just for a couple of milliseconds. In theory keydown function is working and getting the result from response, bt I dont know why just for a very short time.

Any tips?

request.php

<script type="text/javascript">

function post(){
$("#message").keydown(function (e) {
    if (e.keyCode == 13) {
    var message=document.getElementById("message").value;
    $.post('response.php',{postmessage:message},
    function(data){
    var result = $('#post_message').html(data);
    console
return result; });
    }
});
}
</script>

<form>
Enter Message:<input type="text" id="message" name="message" onclick="post()"/><br/>
</form>
<div id="post_message"></div>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
</head>

response.php

<?php
 function returnString() {
    $post_msg = $_POST['postmessage'];
    echo "Message entered ->", $post_msg ," <- here";
}
returnString();
?>

Solution

You are trying to mimic behavior that is already available by default with a form that only has one input.

Thus your form is submitting and reloading the page.

You don't need to listen to key event on the <input>. Just listen for the submit event of the form and prevent the default submit process

$('form').submit(function(e){
    e.preventDefault();    
    var msg = $('#message').val();

    mockPost(msg).then(function(res){        
      $('#post_message').append('<p>' + res + '<p>')
    });    

})


function mockPost(v){
   return new Promise(function(resolve){
        setTimeout(function(){
          resolve('Message= ' + v)
        }, 200)
   })
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form>
Enter Message:<input type="text" id="message" name="message"/><br/>
</form>
<div id="post_message"></div>