Index.php

<div id="ajax-test">
<form method="POST" onsubmit="return false;">
    <textarea onkeyup="loadDoc()" name="someText" id="someText" placeholder="Type something here"></textarea>
        <button type="button" onclick="loadDoc()">Submit</button>
</form>
<div id="ajax-text"></div>
</div>
<script type="text/javascript" src="main.js"></script>

Main.js file

function _(x) {
   return document.getElementById(x);
 }
function ajaxObj ( meth, url ) {
   var x = new XMLHttpRequest();
   x.open( meth, url, true );
   x.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
   return x;
}
function ajaxReturn(x){
   if(x.readyState == 4 && x.status == 200) {
      return true;
   }
}
function loadDoc() {
    var someText = _( "someText" ).value;
    var ajax = ajaxObj( "POST", "ajax/ajax.php" ) ;

    ajax.onreadystatechange = function() {
       if(ajaxReturn(ajax) == true) {
          _('ajax-text').innerHTML = ajax.responseText;
          console.log(ajax.responseText);
       }
    }
  ajax.send("someText="+someText);
 }

ajax/ajax.php file

if(isset($_POST['someText'])){
  $someText = $_POST['someText'];
  echo "\"$someText\"" . ' is what you wrote';
  exit();
} else {
  echo "An error occured";
  exit();
}

VenantCode:
Yeah, but that is kinda old already. With the notion of websockets you don't need to continously poll the server unecessarily.

Laolballs:
Men, with jquery you hlcan reduce the line of code to letsay 8 or leass, i mean jquery ajax is far way better than this, it handles all the browser compatibility issues for ya... Lets embrace technology, let use libraries, it makes live easy and gets the job done faster, i would suggest doing this with jquery, it helps beginners build something meanigul in the shortest possible time, and hey the new html5 server sent event , is as cool as websocket, and not as painful to implement as websocket.......

ANTONINEUTRON:
I Just Got Confuse,

Will Ur Ajax Make The Page Not Reload Before Displaying The User Message "$sometext"

dhtml18:
Exactly, plus if you are dealing with websockets - once you are connected, you do need to call the server at intervals to know if anything is happening, the server itself will call you.

Laolballs:
Men, with jquery you hlcan reduce the line of code to letsay 8 or leass, i mean jquery ajax is far way better than this, it handles all the browser compatibility issues for ya... Lets embrace technology, let use libraries, it makes live easy and gets the job done faster, i would suggest doing this with jquery, it helps beginners build something meanigul in the shortest possible time, and hey the new html5 server sent event , is as cool as websocket, and not as painful to implement as websocket.......

 
ajaxObj( 'method', 'script')
 

document.getElementById(); ==> $ 

document.getElementById('goat'); is the same as _('goat')