CODEWITHSUNDEEP
javascriptarraysjsonlodash
Nikhil Savaliya
Nikhil Savaliya

Reputation: 2166

Find Duplicate value From Collection Using Lodash

Using Lodash I am trying to find if a value exists in the collection or not.

If exists I want to return true else false. 

 const d = [{
     "country": "India",
     "_id": ObjectId("5ad47b639048dd2367e95d48"),
     "cities": []
 }, {
     "country": "Spain",
     "_id": ObjectId("5ad47b639048dd2367e95d49"),
     "cities": []
 }];

Snippet Code

Countries = ['India', 'Spain']
if (_.has(d, Countries)) {
    console.log(true);
} else {
    console.log(false);
}

But it Always returns False. It's not recommended for me to use lodash can anyone suggests a better way if possible.

Upvotes: 0

Views: 4720

Answers (4)

Jackdon Wang
Jackdon Wang

Reputation: 407

Inspired by @Christian Bartram

var cities = [
　　{city: "Beijing",bOn:false},
　　{city: "Shanghai",bOn:false},
　　{city: "Chongqing",bOn:false},
　　{city: "Guangzhou",bOn:false}, {city: "Guangzhou",bOn:true},
　　{city: "Xi'an",bOn:false}
];

//Find duplicate element values in the array
_(cities).groupBy(x => x.city).pickBy(x => x.length > 1).keys().value()

Return

['Guangzhou']

//Find duplicate objects in an array
_.filter(_(cities).groupBy(x => x.city).value(),x => x.length > 1)

Return

[[{"city":"Guangzhou","bOn":false},{"city":"Guangzhou","bOn":true}]]

Upvotes: 0

Narendra Jadhav
Narendra Jadhav

Reputation: 10262

ES6

You could use array.some() and array.includes() for checking duplicate entries in array.

DEMO

const d = [{
  "country": "India",
  "_id": "5ad47b639048dd2367e95d48",
  "cities": []
}, {
  "country": "Spain",
  "_id": "5ad47b639048dd2367e95d49",
  "cities": []
}];

const Countries = ['India', 'Spain'];

console.log(d.some(({country}) => Countries.includes(country)))
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 1

Christian Bartram
Christian Bartram

Reputation: 411

You can also do this without Lodash using Javascripts built in filter function 

d.filter(item => item.country === "Spain"); //Would return an array of objects where the country's name property is Spain!

if we wanted to make this a boolean we could declare it as a variable and assert its length is greater than 0 like so: 

let isSpanishCountry = d.filter(item => item.country === "Spain").length > 0; // console.log(isSpanishCountry) => true

Upvotes: 0

alexmac
alexmac

Reputation: 19607

You can use the combination of some and includes methods. It will return true, if any item in items contains country from countries array. 

const items =  [
    {
        "country": "India",
        "_id": 'ObjectId("5ad47b639048dd2367e95d48")',
        "cities": []
    },
    {
        "country": "Spain",
        "_id": 'ObjectId("5ad47b639048dd2367e95d49")',
        "cities": []
    }
];

const countries = ['India', 'Spain'];
const includes = _.some(items, item => _.includes(countries , item.country));
console.log(includes);
<script src="https://cdn.jsdelivr.net/npm/[email protected]/lodash.min.js"></script>

Upvotes: 4

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