Not able to add key-value in array in Javascript

In this case I need to add role in array and the code below is what I write but it's not work:

async.eachSeries(userArray, (singleUser, callback) => {
                if (singleUser && singleUser.userId && singleUser.userId.userRole) {
                    if (singleUser.userId && singleUser.userId.userRole.includes('trainer') && singleUser.isDelete == false) {
                        // singleUser.isSelected = false;
                        singleUser.roleInJob = "trainer";
                        console.log("singleUser in if", singleUser);
                        trainers.push(singleUser);
                        // callback();
                    }
                    if (singleUser.userId && singleUser.userId.userRole.includes('IQA') && singleUser.isDelete == false) {
                        // singleUser.isSelected = false;
                        singleUser.role = "IQA";
                        singleUser['role'] = 'IQA';
                        console.log("singleUser in if", singleUser);
                        iqa.push(singleUser);
                        // callback();
                    }
                    callback()
                } else {
                    callback();
                }
            }, (callbackError, callbackResponse) => {
                if (callbackError) {
                    reject(callbackError)
                } else {
                    let instructors = {
                        trainers: trainers,
                        iqa: iqa
                    }
                    resolve(instructors)
                }
            })

Any idea how can I solve this problem?