javascript - Uncaught TypeError: Cannot read property 'friends' of null -

i have facebook multifriends selector script shows error.

script:

window.fbasyncinit = function () {      //sdk loaded, initialize      var curloc = window.location;      fb.init({           appid: 'xxxxxxxxxxxxx',          xfbml: true,          version: 'v2.0'      });      (function (d, s, id) {         var js, fjs = d.getelementsbytagname(s)[0];         if (d.getelementbyid(id)) {             return;         }         js = d.createelement(s);         js.id = id;         js.src = "//connect.facebook.net/en_us/sdk.js";         fjs.parentnode.insertbefore(js, fjs);     }(document, 'script', 'facebook-jssdk'));       fb.canvas.setautogrow(); };  function rendermfs() {     // first list of friends user graph api     fb.api('/me/friends', function (response) {         var container = document.getelementbyid('mfs');         var mfsform = document.createelement('form');         mfsform.id = 'mfsform';          // iterate through array of friends object , create checkbox each   one.         (var = 0; < math.min(response.data.length, 10); i++) {             var frienditem = document.createelement('div');             frienditem.id = 'friend_' + response.data[i].id;             frienditem.innerhtml = '<input type="checkbox" name="friends" value="' + response.data[i].id + '" />' + response.data[i].name;             mfsform.appendchild(frienditem);         }         container.appendchild(mfsform);          // create button send request(s)         var sendbutton = document.createelement('input');         sendbutton.type = 'button';         sendbutton.value = 'send request';         sendbutton.onclick = sendrequest;         mfsform.appendchild(sendbutton);     }); }  function sendrequest() {     // list of selected friends     var senduids = '';     var mfsform = document.getelementbyid('mfsform');     (var = 0; < mfsform.friends.length; i++) {         if (mfsform.friends[i].checked) {             senduids += mfsform.friends[i].value + ',';         }     }      // use fb.ui send request(s)     fb.ui({         method: 'apprequests',         to: senduids,         title: 'my great invite',         message: 'check out awesome app!',     }, callback); }  function callback(response) {     console.log(response); }