How to Pass an Object from PHP to Javascript and Back Again Using JSON

Many times I would like to pass an object from my PHP code to Javascript or from Javascript to PHP. JSON and a couple of PHP and Javascript functions make that easy!

JSON is JavaScript Object Notation. Basically, it’s a textual way to represent an object.

To demonstrate, I will create a PHP object:

<?php $test = array('red'=>'apple', 'yellow'=>'banana', 'orange'=>'orange', 'peach'=>'peach') ?>


To pass this to javascript, I need to do this:

<script>
var obj = JSON.parse('<?php echo json_encode($test) ?>');
</script>


If I want to view the object in javascript, I can use the alert function inside the <script> tags like this:

alert(obj.toSource());


I can pass the Javascript Object through Ajax or several other ways. Here is one way to pass the object:

<a id="link" href="">go to script 2</a>
<script>
link = document.getElementById('link');
link.setAttribute('href', 'test2.php?j='+JSON.stringify(obj));
</script>


In my test2.php script, I now need to translate the JSON to a php object again:

$var = $_GET['j'];
print_r(json_decode($var));


And there we have it, back in it’s original object form!