Just want to complete the answer (as I struggled with it for a while), want to show how to access the json information, this example shows accessing Json Array:
var request = require('request');
request('https://server/run?oper=get_groups_joined_by_user_id&user_id=5111298845048832', function (error, response, body) {
if (!error && response.statusCode == 200) {
var jsonArr = JSON.parse(body);
console.log(jsonArr);
console.log("group id:" + jsonArr[0].id);
}
})