Question

How do I ask for a facebook permission?

Chrome blocks the pop up and throws a lot of warning when using FB.login

function askPermission() {
    FB.login( function(response) {
        if(response.authResponse) {
            // Do what I want to do
        }
    }, {scope:'publish_stream'});
}

So instead, I tried this from How to set permission dialog for post message on wall:

function askPermission(appid, redirect_uri, response_type, scope, callback) {
     // Redirect the user back after authorization
     var path = 'https://www.facebook.com/dialog/oauth?';
     var queryParams = ['client_id='+appid, 'redirect_uri='+encodeURI(redirect_uri), 'response_type='+response_type, 'scope='+scope];
     var query = queryParams.join('&');
     var url = path + query;
     top.location.href = url;
}

but it didn’t work as well. I received an error message, something like

“Occurred an error in YourApp. Try again later.”

EDIT:
Chrome still throwed a lot of ‘Unsafe JavaScript attempt to access frame with URL’ even when i tried :

<input type="button" value="Convidar amigos" class="verde" onclick="FB.login(function(response){ if(response.authResponse){post();} }, {scope:'email,publish_stream'});"/>

Answer 1

You should only call FB.login on user interaction (click, submit, etc) or it will be blocked in most browsers. The errors you see are because JS-SDK can’t interact with blocked window.