How to encode 2 dimentional PHP array to Javascript Array?

Which version of PHP are you using ?

With PHP 5.2.10, I get what you're asking for :

$output = array(array(1,1,1,1),array(2,2,2,2),array(3,3,3,3));
$json = json_encode($output);

echo $json . "\n";

Outputs :

$ php temp.php
[[1,1,1,1],[2,2,2,2],[3,3,3,3]]

At least, this is without the JSON_FORCE_OBJECT option -- that was added in PHP 5.3

Maybe you can find something interesting in the user notes on the json_encode manual page ?

For instance, simoncpu says :

A note of caution: If you are wondering why json_encode() encodes your PHP array as a JSON object instead of a JSON array, you might want to double check your array keys because json_encode() assumes that you array is an object if your keys are not sequential.

And if you search for json_encode+array+object on PHP's bugtracker, maybe you'll get some interesting result ?
(For instance, something that says this was a bug, which has been corrected in recent versions of PHP ?)

Your original solution works for me:

adam@fsck:~:0$ php -r 'echo json_encode(array(array(1,1,1,1),array(2,2,2,2),array(3,3,3,3)));'
[[1,1,1,1],[2,2,2,2],[3,3,3,3]]