Sending curl request from js

I was trying to send a request from the fetch() function to my Delhivery API from js application whose format looks like this:-

curl --request POST
--url "https://track.delhivery.com/api/cmu/create.json"
--header "Content-Type:application/json"
--header "Accept:application/json"
--header "Authorization: Token XXXXXXXXXXXXXXXXXX"
--data 'format=json&data={ "shipments": [], "pickup_location": { "name": "Hello", "add": "ABC123", "city": "Delhi", "pin_code": 813210, "country": "India", "phone": "1234567890" } }

I convert it into JSON but it seems it is always unable to detect format parameters.

I tried to send the body like this :

{ format : 'json', data : {......other parameters } }

but it says missing format key in the POST data.

const url = 'https://track.delhivery.com/api/cmu/create.json';

const headers = new Headers({
  'Content-Type': 'application/x-www-form-urlencoded',
  'Accept': 'application/json',
  'Authorization': 'Token XXXXXXXXXXXXXXXXXX'
});

const data = {
  shipments: [],
  pickup_location: {
    name: "Hello",
    add: "ABC123",
    city: "Delhi",
    pin_code: 813210,
    country: "India",
    phone: "1234567890"
  }
};

const formData = new URLSearchParams();
formData.append('format', 'json');
formData.append('data', JSON.stringify(data));

fetch(url, {
  method: 'POST',
  headers: headers,
  body: formData
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error('Error:', error));

try above code and let me what output does this gives, i think it should work.