facebook_graph_api.js (groups members intersection) (deprecated)

/*
 *  config
 */

var token = "XXX";
var limit = 5000;

var id1 = "XXX";
var id2 = "XXX";

/*
 * end config
 */

function getApiUrl(id, token, limit)
{
    return `https://graph.facebook.com/v2.9/${id}/members?access_token=${token}&limit=${limit}`;
}

function getData(url)
{
    var array = [];

    do {
        xhr.open("GET", url, false);
        xhr.send();
        var object = JSON.parse(xhr.responseText);
        array = array.concat(object.data);
        url = object.paging.next;
    } while (url);

    return array;
}

var xhr = new XMLHttpRequest();

var url1 = getApiUrl(id1, token, limit);
var array1 = getData(url1);

var url2 = getApiUrl(id2, token, limit);
var array2 = getData(url2);

var length1 = array1.length;
var length2 = array2.length;

var intersect = [];

for (var i = 0; i < length1; ++i) {
    for (var j = 0; j < length2; ++j) {
        if (array1[i].id == array2[j].id) {
            intersect.push(array1[i]);
        }
    }
}

console.log(intersect);