javascript - json_encode putting empty array on the end of json -

i'm writing ajax application , have function in php script:

public function expire_user() {     $r=array("return"=>'ok');     echo json_encode($r);  } 

that gets called javascript:

$.getjson("/users/expire_user",function(data){         alert('success'); }); 

the problem alert never displays. think due json_encode returning invalid json, because when go url directly, displays

{"return":"ok"}[] 

which not valid json due '[]' on end. why json_encode putting empty array on end , how rid of can receive valid json?

wild guess, maybe should set correct headers json in php function this:

public function expire_user() {     $r=array("return"=>'ok');     header("content-type: application/json");     echo json_encode($r);  } 

or send content x-json headers this:

public function expire_user() {     $r=array("return"=>'ok');     $json_data = json_encode($r);     header('x-json: (' . $json_data . ')');     header('content-type: application/x-json');     echo $json_data; } 

a bit rusty on whether when using x-json accompanying header should application/x-json or normal application/json, adding caveat debug.