Filter unique values from an array of objects [duplicate]

Question

How can I use Array.filter() to return unique id with name ?

My scenario is slightly different than the solutions I have researched in that I have an array of objects. Every example I find contains a flat array of single values.

data=[
{id: 555, name: "Sales", person: "Jordan" },
{id: 555, name: "Sales", person: "Bob" },
{id: 555, name: "Sales", person: "John" },
{id: 777, name: "Accounts Payable", person: "Rhoda" },
{id: 777, name: "Accounts Payable", person: "Harry" },
{id: 888, name: "IT", person: "Joe" },
{id: 888, name: "IT", person: "Jake" },
];

var unique = data.filter(
function (x, i) {
   return data[i].id.indexOf(x.id) === i
});

Thanks in advance.

Mamun · Accepted Answer · 2019-02-07 13:05:16Z

47

I think forEach() is better to achieve what you are looking for:

var data=[
{id: 555, name: "Sales", person: "Jordan" },
{id: 555, name: "Sales", person: "Bob" },
{id: 555, name: "Sales", person: "John" },
{id: 777, name: "Accounts Payable", person: "Rhoda" },
{id: 777, name: "Accounts Payable", person: "Harry" },
{id: 888, name: "IT", person: "Joe" },
{id: 888, name: "IT", person: "Jake" },
];
var resArr = [];
data.forEach(function(item){
  var i = resArr.findIndex(x => x.name == item.name);
  if(i <= -1){
    resArr.push({id: item.id, name: item.name});
  }
});
console.log(resArr);

If you really want to use filter() try the following way:

var data=[
{id: 555, name: "Sales", person: "Jordan" },
{id: 555, name: "Sales", person: "Bob" },
{id: 555, name: "Sales", person: "John" },
{id: 777, name: "Accounts Payable", person: "Rhoda" },
{id: 777, name: "Accounts Payable", person: "Harry" },
{id: 888, name: "IT", person: "Joe" },
{id: 888, name: "IT", person: "Jake" },
];
var resArr = [];
data.filter(function(item){
  var i = resArr.findIndex(x => x.name == item.name);
  if(i <= -1){
    resArr.push({id: item.id, name: item.name});
  }
  return null;
});
console.log(resArr);

edited Feb 7, 2019 at 13:05

answered Apr 12, 2017 at 15:52

Mamun

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7 Comments

bob.mazzo Over a year ago

Yup, that's it ! I was going for a for loop, but I think filter is best.

bob.mazzo Over a year ago

I don't understand why SO jumps to conclusions so quickly re: with a duplicate answer remark. I had searched, but hadn't found the best solution for my scenario.

rablentain Over a year ago

I think that forEach would be better since this approach does not actually use the filter function, since it does not return anything inside the function.

Christopher Kiessling Over a year ago

data = data.reduce((items, item) => items.find(x => x.name === item.name) ? [...items] : [...items, item], [])

Christopher Kiessling Over a year ago

@jinglesthula my bad, use just items in the first ternary branch

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