如何使用spread运算符从对象数组中删除重复项

Question

I have below object array with id as unique key":

var test = [
  {id: 1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""},
  {id: 2, PlaceRef: "*00022", Component: "BAXI10R", SubLocCode: "KIT", BarCode:""},
  {id: 1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""},
  {id: 3, PlaceRef: "*00011", Component: "ANR190", SubLocCode: "B1", BarCode: ""}
]

From this I want to retrieve unique objects using spread operator, I have tried using below code:

const uniKeys = [...(new Set(test.map(({ id }) => id)))];

I am able to retrieve id's only, how can I retrieve the unique objects using spread operator. Also, any new ES6 features implementation would be helpful.

Answer 1

You could map back to array of objects using find method, this will return first object with that id.

 var test = [{id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""},{id:2, PlaceRef: "*00022", Component: "BAXI10R", SubLocCode: "KIT", BarCode:""},{id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""},{id:3, PlaceRef: "*00011", Component: "ANR190", SubLocCode: "B1", BarCode: ""}] var uniq = [...new Set(test.map(({id}) => id))].map(e => test.find(({id}) => id == e)); console.log(uniq) 

You could also use filter method instead.

 var test = [{id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""},{id:2, PlaceRef: "*00022", Component: "BAXI10R", SubLocCode: "KIT", BarCode:""},{id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""},{id:3, PlaceRef: "*00011", Component: "ANR190", SubLocCode: "B1", BarCode: ""}] var uniq = test.filter(function({id}) { return !this[id] && (this[id] = id) }, {}) console.log(uniq) 

Answer 2

You could use a Set and filter by unkown id .

 var test = [{ id: 1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: "" }, { id: 2, PlaceRef: "*00022", Component: "BAXI10R", SubLocCode: "KIT", BarCode: "" }, { id: 1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: "" }, { id: 3, PlaceRef: "*00011", Component: "ANR190", SubLocCode: "B1", BarCode: "" }], unique = test.filter((s => ({ id }) => !s.has(id) && s.add(id))(new Set)); console.log(unique); 

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Answer 3

You could create a Map by id and then extract values. [...new Map(test.map(item => [item.id, item])).values()]

 var test = [{id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""}, {id:2, PlaceRef: "*00022", Component: "BAXI10R", SubLocCode: "KIT", BarCode:""}, {id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""}, {id:3, PlaceRef: "*00011", Component: "ANR190", SubLocCode: "B1", BarCode: ""}] console.log([ ...new Map(test.map(item => [item.id, item])).values() ]) 

Answer 4

 var test = [{id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""}, {id:2, PlaceRef: "*00022", Component: "BAXI10R", SubLocCode: "KIT", BarCode:""}, {id:1, PlaceRef: "*00011", Component: "BATH", SubLocCode: "BAT", BarCode: ""}, {id:3, PlaceRef: "*00011", Component: "ANR190", SubLocCode: "B1", BarCode: ""}]; var uniqArray = Array.from(new Map(test.map(e=>[e.id, e])).values()); console.log(uniqArray) 

Answer 5

Using lodash utility library. you can achieve this. let result = _.uniqBy(test, 'id');