CODEWITHSUNDEEP
javascriptarraysjsonnode.js
SS306
SS306

Reputation: 157

Removing duplicates from JSON array by a value in each JSON object in array

If there are two JSON objects in an array with same value for a particular field, then I want to mark them as duplicate. I want to remove one of them. Similarly, when there are multiple duplicate, I only want to keep the last object(latest).If this is input: 

names_array = [
    {name: "a",  age: 15},
    {name: "a",  age: 16},
    {name: "a",  age: 17},
    {name: "b",  age: 18}
    {name: "b",  age: 19}];

I want the output to be

names_array_new = 
    {name: "a",  age: 17},
    {name: "b",  age: 19}];

I have searched for this but only found how to remove duplicates when entire objects are same.

Upvotes: 4

Views: 17150

Answers (4)

B Vanitha
B Vanitha

Reputation: 26

Array.from(new Set(brand.map(obj => JSON.stringify(obj)))).map(item => JSON.parse(item))

Upvotes: 0

kiran Sp
kiran Sp

Reputation: 153

var names_array = [
{name: "a", age: 15},
{name: "a", age: 16},
{name: "a", age: 17},
{name: "b", age: 18},
{name: "b", age: 19}];

function removeDuplicate(arr, prop) {
var new_arr = [];
var lookup = {};
for (var i in arr) {
    lookup[arr[i][prop]] = arr[i];
}
for (i in lookup) {
    new_arr.push(lookup[i]);
}
return new_arr;}
var newArray = removeDuplicate(names_array, 'name');
console.log("Result "+newArray);

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386540

A slightly different approach:

var names_array = [
    { name: "a", age: 15 },
    { name: "a", age: 16 },
    { name: "a", age: 17 },
    { name: "b", age: 18 },
    { name: "b", age: 19 }
];

var names_array_new = names_array.reduceRight(function (r, a) {
    r.some(function (b) { return a.name === b.name; }) || r.push(a);
    return r;
}, []);

document.getElementById('out').innerHTML = JSON.stringify(names_array_new, 0, 4);
<pre id="out"></pre>

Upvotes: 1

codebox
codebox

Reputation: 20254

This should do it:

names_array = [
    {name: "a",  age: 15},
    {name: "a",  age: 16},
    {name: "a",  age: 17},
    {name: "b",  age: 18},
    {name: "b",  age: 19}];

function hash(o){
    return o.name;
}    

var hashesFound = {};

names_array.forEach(function(o){
    hashesFound[hash(o)] = o;
})

var results = Object.keys(hashesFound).map(function(k){
    return hashesFound[k];
})

The hash function decides which objects are duplicates, the hashesFound object stores each hash value together with the latest object that produced that hash, and the results array contains the matching objects.

Upvotes: 5

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