var ar1 = [
{ amount: 73, date: '1605015361' },
{ amount: 115, date: '1605018961' },
{ amount: 135, date: '1605022560' },
{ amount: 75, date: '1605026160' }
];
function converter(array) {
for (let x = 0; x < array.length; x++) {
var neww = new Date(array[x].date * 1000).toLocaleDateString("en-US")
console.log(neww);
array[x].date = neww
}
}
converter(ar1);
console.log(ar1);