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I am writing a validation mechanizm for my website. Some code is used with Javascript and ajax to validate (mostly lengths of) strings. And some other code is used in php on the server side.

Both PHP and Javascript need to use the same vars, say MAX_USERNAME_LENGTH. So that they stay in sync, and save on development time up front.

I was thinking of using JSON. But after researhing a little I noticed that:

$.getJSON("http://myurl.com/vars.json", function(json) {
  alert(json['MAX_USERNAME_LENGTH']);
})

for starters, this for some reason won't access a local location as ../includes/vars.json, and returns 404 for some reason....

  1. I was thinking, if I put this in the $(document).ready(function () then all the code would run, but the vars themselves would not have loaded if the network was slow....

Is there a way to simply do something like :

var json=parseJsonFromLocalFile("../includes/vars.json");

I need this also for the php, but there I think it would be easier using json_decode() Thanks in advance!!!

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What do you mean by a local file? On the client or server side? – bcoughlan Jul 17 '11 at 19:14
Oh soryy. I meant the server side. I want the file to be included, and be synchronous with the whole object model. I mean, I want the vars to be included, and only then used, whereas in the example I gave before, the vars might be used without being read due to network latency. – Ted Jul 17 '11 at 20:58
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1 Answer

up vote 2 down vote

You could create a Javascript file instead of a JSON one - just define all your variables in a PHP array, then make a PHP file with contents like:

var config = <?php echo json_encode($config); ?>;

and load it like:

<script type="text/javascript" src="../includes/vars.php"></script>

(vars.js would be a better name, but would require that your server knew to process *.js files as PHP.)

This will load your variables synchronously, and gets them into the global scope more easily than an asynchronous JSON load.

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That's a great approach, only that I need the same php file serve the php side as well. That means that when I require_once("vars.php"); It would not compile with the var config = part. – Ted Jul 17 '11 at 21:04
I meant: use a GET method and set the code accordingly ? <?php if($_GET['selector']=='javascript') echo 'var json= '; if($_GET['selector']=='php') echo '$json = '; if (($_GET['selector']=='javascript') || ($_GET['selector']=='php')) echo'{"MAX_USERNAME_LENGTH":"12","BOX_COLOR":"#254ff3"}'; – Ted Jul 17 '11 at 21:35
But here's a new problem. I need to #include that vars file in the js file...... – Ted Jul 17 '11 at 21:36
and this way isn't a GET either.... – Ted Jul 17 '11 at 22:45
@Ted - If I were you, I'd define the configuration variables as an array in PHP, in some centrally located includes/config.php file. Then when you need to use it in PHP, just include the config.php file in your code (no deserialization from JSON necessary); when you need to use it in JS, include it at the top of the script I detail above and json_encode it. – nrabinowitz Jul 18 '11 at 5:33
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