Handle php which get ajax json request

Question

Suppose I run this ajax -

$.ajax({
    url: "index.php",
    type: 'POST',
    data :{test : 123}, //updated due to the approved answer
    dataType: 'json'
});

and I want to get its json content in - index.php and alert its test value (mean get - 123 ) ,

I tried this -

index.php-

<?php
    $json = $_POST["test"];
    echo '<script>';
    echo 'alert('+$json+');';
    echo '</script>';
?>

but nothing was alerted .

How to handle it correctly ?

Update:

Following @JayBlanchard comment,

does $json = $_POST["test"] is really get the test value ?

The alert isn't important for me , I just want to ensure whether it's parsed correctly in the PHP side , mean get the 123 back to the client side .

Answer 1

You need to handle the results from your php in your JavaScript callback. So you could do this:

$.ajax({
    url: "index.php",
    type: 'POST',
    data :{text : 123},
    dataType: 'json',
    complete: function(data){
        console.log(data.responseText) //(not sure why responseText is necessary)
    }
});

Your php would be something like:

<?php
$json = $_POST["text"];
echo $json;
?>

Answer 2

You would do this simply in the success callback:

$.ajax({
    url: 'index.php',
    type: 'post',
    data: {text : 123},
    dataType: 'json',
    success: function(data) {
       alert(data.test);
    }
});

And your index.php :

<?php
    echo json_encode(array('test' => $_POST['test']));
?>

Answer 3

You have to define a javascript function to handle response:

var handle_response = function(data_from_server, StatusText, jqxhr) {
    // check http://api.jquery.com/jquery.ajax/ for StatusText and jqxhr meaning.
    alert(data_from_server);
}

Then you call your ajax

$.ajax({
    url: "index.php",
    type: 'POST',
    data :{text : 123},
    dataType: 'json',
    success: handle_response
});

your php will be something like

<?php
    $json = json_decode($_POST["text"]);  // not sure about dataType: 'json'

    echo "this is coming from php on server ";
?>

if you want to execute some script created from the server check on jquery manual how to do it safely.