你可以试试这个:

const 结果 = Object.values(data.reduce((r, o) => (r[o.id]?(r[o.id].total += o.total): (r[o.id] = {...o}), r), {}));

i need help with this, i need group by id and sum, but i need a new object for each result

let data =[
    {"id":"2018", "name":"test", "total":1200},
    {"id":"2019", "name":"wath", "total":1500},
    {"id":"2019", "name":"wath", "total":1800},
    {"id":"2020", "name":"zooi", "total":1000},
]

i have this code that return just one object with the result

let result = data.reduce(function (r, o) {
    (r[o.id])?
        r[o.id] += o.total:
        r[o.id] = o.total; 
    return r;
});

but i need some like this

[
    {"id":"2018", "name":"test", "total":1200},
    {"id":"2019", "name":"wath", "total":2300},
    {"id":"2020", "name":"zooi", "total":1000},
]

any suggestion?, thanks

You can try this:

const result = Object.values(data.reduce((r, o) => (r[o.id]
  ? (r[o.id].total += o.total)
  : (r[o.id] = {...o}), r), {}));