Jcan,
I'm not a json peron but I would guess that json would offer a very compact way to do this.
The good news for non-json folks is that standard javascript is also very compact for an indexed array comprising numbers or strings or a mixture of the two. It gets more complex if it contains objects and/or is associative, but not insurmountable.
For the simple case (numbers and strings):
delimiter = '^';
var myPostString = myArray.join(delimiter);
Choose a delimiter that will never appear in your arrays. It can be multiple characters if you want, eg,
delimiter = '£%^&'; .
Then use the most appropriate technique for building your post (ie HTML form vs ajax http request object). I'm guessing you know how to do this.
Server-side, in php, simply use explode() to convert the posted string back to an array:
$delimiter = '^';
$myVar = explode(delimiter, $_POST['myVar']);
At this point it will be an array of strings - it can't be otherwise. Because php automatically type converts, much like js, you may not need to explicitly convert numbers back, but it may depend on what you are going to do with the values. Just be aware.
Hope this helps.
Airshow