如何获取数组中的重复对象？

Question

I have an array like this:

    var clients=[{"id":1,"name":"john","age":20},
{"id":3,"name":"dean","age":23},
{"id":12,"name":"harry","age":14},
{"id":1,"name":"sam","age":22},
{"id":13,"name":"Bolivia","age":16},
{"id":7,"name":"sabi","age":60},
{"id":7,"name":"sahra","age":40},
{"id":4,"name":"natie","age":53},{"id":7,"name":"many","age":22}]

I want to find the duplicate objects and cluster them like this:

 [
       {
       "id":1,
        "clients":[
                    {"id":1,"name":"john","age":20},
                    {"id":1,"name":"sam","age":22}
                   ]
       },
     {
       "id":7,
       "clients":[
                   {"id":7,"name":"sabi","age":60},
                   {"id":7,"name":"sahra","age":40},
                   {"id":7,"name":"many","age":22}
                  ]
      }
    ]

can I do that with filter() like this: clients.filter(//code hier) ?

Answer 1

reduce() is tailor made for this. When you want to aggregate over an array and get a computed result, you should use reduce() .

find() is another array method, which helps in finding an array element based on a condition (here the matching of id property).

 var clients=[{"id":1,"name":"john","age":20}, {"id":3,"name":"dean","age":23}, {"id":12,"name":"harry","age":14}, {"id":1,"name":"sam","age":22}, {"id":13,"name":"Bolivia","age":16}, {"id":7,"name":"sabi","age":60}, {"id":7,"name":"sahra","age":40}, {"id":4,"name":"natie","age":53},{"id":7,"name":"many","age":22}] let ans = clients.reduce((agg,x,index) => { let findI = agg.find( a => a.id === x.id ); if(findI) findI.clients.push(x); else { agg.push({ id: x.id, clients: [x] }); } return agg; },[]); console.log(ans);

Answer 2

The simplest solution would be to loop over the clients and check for an existing object with the same id . If yes, push to clients array. Or else, just create one.

 var clients = [{ "id": 1, "name": "john", "age": 20 }, { "id": 3, "name": "dean", "age": 23 }, { "id": 12, "name": "harry", "age": 14 }, { "id": 1, "name": "sam", "age": 22 }, { "id": 13, "name": "olivia", "age": 16 }, { "id": 7, "name": "sabi", "age": 60 }, { "id": 7, "name": "sahra", "age": 40 }, { "id": 4, "name": "natie", "age": 53 }, { "id": 7, "name": "kany", "age": 22 }] const groups = []; for (let client of clients) { const existingGroup = groups.find(group => group.id == client.id) if (existingGroup) existingGroup.clients.push(client); else { groups.push({ id: client.id, clients: [client] }); } } console.log(groups);

You can reassign the original object with the temporary object just used for this, and continue with your business logic, which I believe is the one you are looking for.