about function

Question

function groupById(array) {
return array.reduce((obj, value) => {
obj[value.id] = value;
return obj;
}, {})
}

i want to known after return obj;
{}) what is this?

Answer 1

empty object literal
used as initial value of reduce accumulator (obj argument of callback function)

Answer 2

Lokesh Rathi You posted same question twice delete that