Using javascript sdk to call facebook api

Question

Using javascript sdk to call facebook api

I am trying to use the Facebook API Javascript SDK to check if a Facebook page (not a profile, just a place page) exists or not. I am using two separate files, one HTML with a simple form in it and a script that calls the facebook api. However, the FB.api method doesn't seem to return anything. I don't have much experience with api, so I would appreciate any help.

Html file code:

    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
    <link rel="stylesheet" type="text/css" href="style_admin.css" />
     <script src="http://connect.facebook.net/en_US/all.js"   type="text/javascript"></script>
     <script type="text/javascript" src="url_ver.js"></script>
 </head>

 <body>
    <form action="" method="post"  onsubmit="verifyUrl()">
    URL: <input id="url" type="text" name="page" ><br><br>
    <input  type="submit" value="Submit"  >
    </form>



  </body>
</html>

.js script:

function verifyUrl(){
  var page_id=document.getElementById("url").value;
  if(page_id){

        var i=page_id.lastIndexOf('/');
        var q=page_id.indexOf('?');
        var id=0;
        if (q>0){
            id=page_id.substring(i,q);
        }else{
            id=page_id.substr(i,id.length);
        }

        alert(id); 
        FB.init({
        appId      : <myappid>,
        xfbml      : true,
        version    : 'v2.3'
        });


        FB.api(id,function(response){
        if (!response || response.error) {
            alert('Error occured');
        } else {
            alert('Response ID: ' + response.id);
         }

       });


}