Ajax for laravel 4

I'm trying to set up ajax for laravel, but it won't work. I have controller for posting comments. javascript which blocks the submit button and sends ajax which is returning 500 error

public function postComment()
{
    if (Request::ajax()) 
    {
        return Response::json(['blah' => 'ohhh']);
        }
}

    $('#submit_comment').click(function (e)
{
    e.preventDefault();

    $.ajax({
        type : "POST",
        url : "http://page.dev/posts/comment",
        data : 
        {
            comment : $("#comment_area").text()
        }
    });

});

<script type="text/javascript">var comment = "{{URL::action('PostsController@postComment')}}"; </script>

What it returns is 500 internal server error

UPD:

    Route::get('posts/{id}', ['as' => 'post', 'uses' => 'PostsController@getShow'])->where('id', '\d+'); // Where id == number
Route::get('category/{id}', ['as' => 'category', 'uses' => 'PostsController@getCategory'])->where('id', '\d+');

SOLUTION: I used in constructor csrf protection. after i removed csrf protection from postComment it worked for me Route::controller('posts', 'PostsController');

It is difficult to to offer advice without seeing your route, controller, view code neatly separated. However, this is the bare minimum necessary to achieve your desired outcome:

In your routes.php

Route::post('/comment', function()
{
    return Response::json(['blah' => 'ohhh']);
});

In your view:

$.ajax({
    type : "POST",
    url : "comment",
});

if you are getting a 500 response then it is likely that you have a problem with your route to controller@postComment.