Share Constants Between PHP and JavaScript

I have several constants in a PHP application I'm developing. I've defined a Constants class and the defined the constants as const VAR_NAME = value; in this class. I would like to share these constants between my JavaScript and PHP code. Is there a DRY (Don't Repeat Yourself) mechanism to share them?

class Constants {
    const RESOURCE_TYPE_REGSITER = 2;
    const RESOURCE_TYPE_INFO = 1;
}

From stackoverflow

• I would use json_encode. You will have to convert the class to an associative array first.

  $constants = array("RESOURCE_TYPE_REGISTER"=>2, "RESOURCE_TYPE_INFO"=>2);
  echo json_encode($constants);
  

  You could also use reflection to convert the class to an associative array if you would prefer to use a class.

  function get_class_consts($class_name)
  {
      $c = new ReflectionClass($class_name);
      return ($c->getConstants());
  }
  
  class Constants {
      const RESOURCE_TYPE_REGSITER = 2;
      const RESOURCE_TYPE_INFO = 1;
  }
  
  echo json_encode(get_class_consts("Constants"));
  

  Gumbo : You mixed JavaScript and PHP syntax. There is no JSON object in PHP. There are just json_*() functions.

  Adam Peck : Oops. I have updated it so there is no confusion :D

  Brian Fisher : This is great, however, get_class_vars seems to skip the const variables in the class.

  Crescent Fresh : Heh. Nice patching.

  Adam Peck : Hey at least it's right now :) Although I still think the simplest way is to leave it in an associative array. And this time I actually tested it too!

  Brian Fisher : Thanks, this works great. I like using the const member variables instead of an associative array, because my IDE can then do code completion.

• The only way you can share the constants is to have the php side inform the javascript. For instance:

  echo "<script> var CONSTANT1 =".$constant_instance->CONSTANT_NAME.";</script>";
  

  Or using ajax, you could also write a small script that would return the constants as JSON/whatever.

• A bit of an ugly hack, but here it goes:

  constants.js

  //<?php
  $const1 = 42;
  $const2 = "Hello";
  //?>
  

  constants.html (use inside JavaScript)

  <script type="text/javascript" src="constants.js"></script>
  <script type="text/javascript">document.write($const1);</script>
  

  constants.php (use inside PHP)

  <?php
  ob_start(); // start buffering the "//"
  require "constants.js";
  ob_end_clean(); // discard the buffered "//"
  
  echo $const1;
  ?>
  

  Ates Goral : I knew this answer would get downvotes! :)