formdata.entries() not a function in react native

i am adding a key and value to formdata, and when i try to console.log() it says data.entries not a function. i tried consoling it directly it shows like this

{
"_parts": [
    [
        "referral_product[0]",
        "rgvsrh_09"
    ]
]

}

here is my code

 var formdata= new FormData();
  formdata.append('referral_product[0]', `${props.Refferel}_${props.product_id}`);
  for (var pair of formdata.entries()) {
    console.log(pair[0]+ ', ' + pair[1]); 
}