Passing PHP JSON to Javascript: echo json_encode vs echo json declaration

Question

I'm trying to create a common constants file to share between php and javascript, using JSON to store the constants. But I'm wondering why pass the JSON from PHP to javascript using json_encode() over echoing the json declaration.

Let's say I have the PHP JSON

<?php 

$json_obj = '{"const1": "val",
            "const2": "val2"             
                            }';

?>

Googling, it seems the typical way of passing back to javascript is using

<?php echo json_encode($json_obj); ?>

Then I believe I would have to use something like $.getScript() to read the php file to get $json_obj and then use parseJSON() to make it useable in javascript.

But why not instead

<?php  echo 'var json = '.$json_obj; ?>

This way all you have to do is load the script directly and you have the json ready to use directly.

Is there a particular reason why it is more favorable to use json_encode() then simply echoing the declaration to javascript?

Answer 1

Passing PHP JSON to Javascript and reading

var data = <?php echo json_encode($json); ?>;
var arr = new Array();
arr = JSON.parse(data);
document.write( arr[0].something );