Je crois qu'il demande d'écrire le nouveau json dans un répertoire. Vous aurez besoin de Javascript y PHP. Donc, pour faire suite aux autres réponses :
script.js
var yourObject = {
test:'test 1',
testData: [
{testName: 'do',testId:''}
],
testRcd:'value'
};
var myString = 'newData='+JSON.stringify(yourObject); //converts json to string and prepends the POST variable name
$.ajax({
type: "POST",
url: "buildJson.php", //the name and location of your php file
data: myString, //add the converted json string to a document.
success: function() {alert('sucess');} //just to make sure it got to this point.
});
return false; //prevents the page from reloading. this helps if you want to bind this whole process to a click event.
buildJson.php
<?php
$file = "data.json"; //name and location of json file. if the file doesn't exist, it will be created with this name
$fh = fopen($file, 'a'); //'a' will append the data to the end of the file. there are other arguemnts for fopen that might help you a little more. google 'fopen php'.
$new_data = $_POST["newData"]; //put POST data from ajax request in a variable
fwrite($fh, $new_data); //write the data with fwrite
fclose($fh); //close the dile
?>