AJAX - Using POST instead of GET

Up until now I have been using:

xmlhttp.open("GET","server_script.php?q="+str,true);

Thanks

Edit: I am providing a solution for anyone that may come across this page to demonstrate how to use POST instead of GET. If you are new to AJAX I would recommend this tutorial http://www.w3schools.com/PHP/php_ajax_php.asp using the GET method first.

Solution-

javascript:

xmlhttp.open("POST","script.php",true);
xmlhttp.setReque开发者_运维技巧stHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send('var_name='+str);

php:

$var_name = GET['var_name'];

echo $var_name;

For reasons regarding the use of POST and GET - see comments blow.

this is how you would use post:

var url = "server_script.php";
var params = "q="+str;
xmlhttp.open("POST", url, true);

//Send the proper header information along with the request
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.setRequestHeader("Content-length", params.length);
xmlhttp.setRequestHeader("Connection", "close");

xmlhttp.onreadystatechange = function() {//Call a function when the state changes.
    if(xmlhttp.readyState == 4 && xmlhttp.status == 200) {
        alert(xmlhttp.responseText);
    }
}
xmlhttp.send(params);

source

The query you show is probably perfectly fine as a GET request. No need to change it.

There are reasons to use one over the other: Requests that change state on server side (i.e. change data) should generally use POST; "read" requests should be GET.

This comes with an implicit security advantage because you can't do any damage by smuggling an URL into a user's page (like, showing an image whose URL points to an admin page named deleteall.php).

If your request just retrieves data, you're perfectly fine staying with GET.

See this question for an extensive discussion on when to use which. GET vs POST in AJAX?