TypeError: Object has no member 'map'

Grafana k6 OSS Support
1

Given a function:

function manipulateValidateReqRes (bearerToken) {
const res = validateExcelResponse.json().data
/* res value is:
{
        "valid_data": [
            {
                "shipper_name": "automate sender",
                "rts_reasons": [
                    "a reason"
                ],
                "rts_score": 0
            }
        ],
        "shipping_rates": [
            {
                "reguler": {
                    "summary_price": "7.000",
                    "data": [
                        {
                            "_s": "9917",
                        }
                    ]
                }
            }
        ],
        "errors": [
            [],
            []
        ]
    }

*/

const manipulateRequest = res.map((obj, index) => {
    return {
                _s: res.data.shipping_rates[index].reguler.data[index]._s
}
}
}

why i cant return _s from map res.map function? it says TypeError: Object has no member ‘map’