Getting an object from an array of objects by object property/field: functional way? (JavaScript / ES6) [duplicate]

Question

I have a JavaScript array of objects (essentially originating from JSON data from a web service), where each object represents a country:

let countries = [ ..., { "id": 46, "type": "COUNTRY", "name": "Cape Verde", "isoCode": "CV", "isoNbr": "132" }, { "id": 52, "type": "COUNTRY", "name": "Christmas Island", "isoCode": "CX", "isoNbr": "162" }, { "id": 63, "type": "COUNTRY", "name": "Cyprus", "isoCode": "CY", "isoNbr": "196" }, { "id": 64, "type": "COUNTRY", "name": "Czech Republic", "isoCode": "CZ", "isoNbr": "203" }, { "id": 88, "type": "COUNTRY", "name": "Germany", "isoCode": "DE", "isoNbr": "276" }, { "id": 66, "type": "COUNTRY", "name": "Djibouti", "isoCode": "DJ", "isoNbr": "262" }, ... ]; 

QUESTION:

How do you best get the entry by isoCode here?

Maybe I have to turn this into a map (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) beforehand, with the isoCode being the key and the value being the unchanged object...??

let mapOfCountries = turn_into_map(countries); selectedCountry = mapOfCountries[this.selectedEntity.countryCode]; // or even simpler: // selectedCountry = mapOfCountries['DE']; 

How do you best do this in JavaScript / ES6? Maybe a functional approach? I'd rather not like to use a for loop here and check manually. Yuk.

Answer 1

You could use Object.fromEntries to create your map and then access it simply by country code e.g.

const mapOfCountries = Object.fromEntries( countries.map(o => [o.isoCode, o]) ); console.log(mapOfCountries['DE']) 

let countries = [ { id: 46, type: "COUNTRY", name: "Cape Verde", isoCode: "CV", isoNbr: "132" }, { id: 52, type: "COUNTRY", name: "Christmas Island", isoCode: "CX", isoNbr: "162" }, { id: 63, type: "COUNTRY", name: "Cyprus", isoCode: "CY", isoNbr: "196" }, { id: 64, type: "COUNTRY", name: "Czech Republic", isoCode: "CZ", isoNbr: "203" }, { id: 88, type: "COUNTRY", name: "Germany", isoCode: "DE", isoNbr: "276" }, { id: 66, type: "COUNTRY", name: "Djibouti", isoCode: "DJ", isoNbr: "262" } ]; const mapOfCountries = Object.fromEntries( countries.map(o => [o.isoCode, o]) ); console.log(mapOfCountries['DE']); console.log(mapOfCountries['CZ']);

Answer 2

Just use the find(...) method:

const countries=[{id:46,type:"COUNTRY",name:"Cape Verde",isoCode:"CV",isoNbr:"132"},{id:52,type:"COUNTRY",name:"Christmas Island",isoCode:"CX",isoNbr:"162"},{id:63,type:"COUNTRY",name:"Cyprus",isoCode:"CY",isoNbr:"196"},{id:64,type:"COUNTRY",name:"Czech Republic",isoCode:"CZ",isoNbr:"203"},{id:88,type:"COUNTRY",name:"Germany",isoCode:"DE",isoNbr:"276"},{id:66,type:"COUNTRY",name:"Djibouti",isoCode:"DJ",isoNbr:"262"}]; console.log(countries.find(c => c.isoCode === 'DJ'))

Also, for your information - on the link provided, you can see a lot more resources on JavaScript. I recommend you to read through it, its pretty interesting :)