How to remove duplicate names from array of objects

Question

var arr = [
    {level:0,name:"greg"},
    {level:0,name:"Math"},
    {level:0,name:"greg"}
];

I have tried the following:

function removeDuplicates:(dataObject){
    self.dataObjectArr = Object.keys(dataObject).map(function(key){
        return dataObject[key];
    });

    for(var i= 0; i < self.dataObjectArr.length; i++ ){
        self.dataObjectArr[i]['name'] = self.dataObjectArr[i];

        self.uniqArr = new Array();
        for(var key in self.dataObjectArr){
            self.uniqArr.push(self.dataObjectArr[key]);
        }
    }
    self.uniqObject = DataMixin.toObject(self.uniqArr);
    return self.uniqObject;
}

But I get error saying: Uncaught TypeError: Converting circular structure to JSON.

Seems your function declaration has an : here -> function removeDuplicates:(dataObject) ? — David R
– David R, Commented Sep 28, 2016 at 7:10
You can use underscore check this answer stackoverflow.com/questions/9923890/… — Davide
– Davide, Commented Sep 28, 2016 at 7:14

Pranesh Ravi · Accepted Answer · 2016-09-28 07:20:01Z

2

You should push the name to an array or a set and check the same in the following..

var arr = [{
  level: 0,
  name: "greg"
}, {
  level: 0,
  name: "Math"
}, {
  level: 0,
  name: "greg"
}]

function removeDuplicates(arr) {
  var temp = []
  return arr.filter(function(el) {
    if (temp.indexOf(el.name) < 0) {
      temp.push(el.name)
      return true
    }
  })
}

console.log(removeDuplicates(arr))

answered Sep 28, 2016 at 7:20

Pranesh Ravi

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7 Comments

kittu Over a year ago

What is temp.indexOf(el.name) < 0 doing?

kittu Over a year ago

less than 0 mean -1(not found)?? Could you please explain

Pranesh Ravi Over a year ago

Exactly, if not found, indexOf() will return -1

kittu Over a year ago

I know that but how is it removing duplicates with this logic I am not able to understand

Pranesh Ravi Over a year ago

I'm not returning false explicitly. If nothing is returned, it'll be taken as undefined, which is the same like false

|

Community · Accepted Answer · 2017-05-23 12:19:20Z

2

Here's a generic "uniquify" function:

function uniqBy(a, key) {
    var seen = new Set();
    return a.filter(item => {
        var k = key(item);
        return !seen.has(k) && seen.add(k)
    });
}

///

var arr = [
    {level:0,name:"greg"},
    {level:0,name:"greg"},
    {level:0,name:"joe"},
    {level:0,name:Math},
    {level:0,name:"greg"},
    {level:0,name:"greg"},
    {level:0,name:Math},
    {level:0,name:"greg"}
];

uniq = uniqBy(arr, x => x.name);
console.log(uniq);

See here for the in-depth discussion.

edited May 23, 2017 at 12:19

CommunityBot

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answered Sep 28, 2016 at 7:18

georg

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Comments

Federico · Accepted Answer · 2016-09-28 07:24:13Z

0

I believe you have a syntax error " removeDuplicates:(dataObject){ ..."

should be without the ":" >> " removeDuplicates(dataObject){ ... " "

You can try this :

function removeDuplicates(arr){
    var match={}, newArr=[];
    for(var i in arr){ if(!match[arr[i].name]){ match[arr[i].name]=1; var newArr=i; } }
    return newArr;
}

arr = removeDuplicates(arr);

answered Sep 28, 2016 at 7:24

Federico

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Comments

guest271314 · Accepted Answer · 2016-09-28 07:46:54Z

0

You can use $.unique(), $.map(), $.grep()

var arr = [
  {level:0,name:"greg"},
  {level:0,name:"Math"},
  {level:0,name:"greg"}
];

var res = $.map($.unique($.map(arr, el => el.name)), name => 
            $.grep(arr, el => el.name === name)[0]);

jsfiddle https://jsfiddle.net/4tex8xhy/3

edited Sep 28, 2016 at 7:46

answered Sep 28, 2016 at 7:30

guest271314

1

Comments

Vladimir M · Accepted Answer · 2016-09-28 07:48:36Z

0

Or you can use such libraries as underscore or lodash (https://lodash.com/docs/4.16.2). Lodash example:

var arr = [
    {level:0,name:"greg"},
    {level:0,name:"Math"},
    {level:0,name:"greg"}
];

var result = _.map(_.keyBy(arr,'name'));

//result will contain
//[
//   {
//    "level": 0,
//    "name": "greg"
//    },
//    {
//    "level": 0,
//    "name": "Math"
//    }
//]

Ofc. one thing to always consider in these tasks, what do you want exactly are you going to do: modify an existing array, or get a new one back. This example returns you a new array.

answered Sep 28, 2016 at 7:48

Vladimir M

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