Php and Json Examples ...

Here we can write our first AJAX script. We will need two new functions for that, first which will dynamically get content from other file, and another one which will be catching external file download status:

var request;
 
function getContent()
{
    request = getHTTPObject();
    request.onreadystatechange = sendData;
    request.open("POST", "load.html", true);
    request.send(null);
}
 
function sendData()
{
    var dC = document.getElementById("dCo");
    if(request.readyState == 4)
    {
        dC.innerHTML = request.responseText;
    }
    else if(request.readyState == 1)
    {
        dC.innerHTML = "<img src="loading.gif" alt="" /> Requesting content..."
    }
}

JSON and PHP:

Decoding JSON string is very simple with PHP only one line of code is needed to parse string into object. Similary only one function is needed to encode PHP object or array into JSON string, look at the code:

<?php
 
// decode JSON string to PHP object
$decoded = json_decode($_GET[json]);
 
// do something with data here
 
// create response object
$json = array();
$json[errorsNum] = 2;
$json[error] = array();
$json[error][] = Wrong email!;
$json[error][] = Wrong hobby!;
 
// encode array $json to JSON string
$encoded = json_encode($json);
 
// send response back to index.html
// and end script execution
die($encoded);
 
?>

It is also interesting what is inside $decode variable

stdClass Object
(
    [firstname] => fgfg
    [email] =>
    [hobby] => Array
        (
            [0] => stdClass Object
                (
                    [hobbyName] => sport
                    [isHobby] => 1
                )
 
            [1] => stdClass Object
                (
                    [hobbyName] => reading
                    [isHobby] =>
                )
 
            [2] => stdClass Object
                (
                    [hobbyName] => music
                    [isHobby] =>
                )
 
        )
)

PHP finished execution, then “request” object status in JavaScript is now equal to 4. Response text (in sendData() function) will be parsed with JSON class to object and used to display message on the screen. Note that instead of using JSON.parse() we could use JavaScriipt eval() function.

 Original Source: