how to update object of array with new object in react native

So you'll want to loop through each item the logicalAddress array and compare it with your object. Like you say, for the comparison we want to look for whether orderNo exists and if it matches any orderNo in the array. Assuming you are using ES6 that might look something like.

const logicalAddress = [
  {
    orderNo: 'AB1',
    RelNo: '001',
    denomination: 'Testing',
    lineNo: '09',
    quantity: '4000',
  },
  {
    orderNo: 'AB2',
    RelNo: '',
    denomination: 'Testing',
    lineNo: '',
    quantity: '5000',
  },
];

const obj = {
  orderNo: 'AB2',
  RelNo: '',
  denomination: 'Testing',
  lineNo: '',
  quantity: '8000',
};

let objMatch = false;

if (obj.orderNo) { // If we have an order number
  logicalAddress.forEach((address, i) => { // Loop array
    if (address.orderNo === obj.orderNo) { // If address and obj numbers match
      // Update value
      logicalAddress[i] = obj;
      objMatch = true;
    }
  });
}

if (!objMatch) { // If after looping through we have no match
  logicalAddress.push(obj); // Add obj to array
}

let logicalAddress = [
{
  orderNo: 'AB1',
  RelNo: '001',
  denomination: 'Testing',
  lineNo: '09',
  quantity: '4000',
},
{
  orderNo: 'AB2',
  RelNo: '',
  denomination: 'Testing',
  lineNo: '',
  quantity: '5000'
}
];

const obj = {
orderNo: 'AB2',
RelNo: '',
denomination: 'Testing',
lineNo: '',
quantity: '8000',
};

Find whether the record is presented or not in array. If yes then get the index of it using findIndex and remove it and push else directly push it.

const objIndex = logicalAddress.findIndex(address => address.orderNo === 
obj.orderNo);

if(objIndex !== -1){
  logicalAddress.splice(objIndex);
 }

 logicalAddress.push(obj);

 console.log(logicalAddress);