ループ内にオブジェクトを作成する

Question

私は会社と国とのjsonファイルを持っています。オブジェクトを作成する最も正しい方法は何ですか。サイクルはすべての国を行き来します。その結果、オブジェクトを結果として取得するために、特定の国に関連する企業の数を計算する必要があります。次の形式です。

country = { 
    USA: 13, 
    Germany: 11, 
    Belgia: 3 
} 

Answer 1

あなたはこのような何かを試すことができます（あなたが編集する前にあなたの質問に持っていたオブジェクトデータを使用した。）あなたはに

var jsondata = {"list":[{"name":"Photolist","location":{"name":"Poland","code":"PL"},"partners":[{"name":"Oloo","value":30},{"name":"Flashset","value":87}]},{"name":"Mymm","location":{"name":"Ukraine","code":"UA"},"partners":[{"name":"Photojam","value":57},{"name":"Divavu","value":82},{"name":"Quinu","value":18}]},{"name":"Yata","location":{"name":"United States","code":"US"},"partners":[{"name":"Meetz","value":72}]},{"name":"Brainbox","location":{"name":"Norway","code":"NO"},"partners":[{"name":"Divavu","value":42}]},{"name":"Flashpoint","location":{"name":"Sweden","code":"SE"},"partners":[{"name":"Babbleopia","value":53},{"name":"Buzzdog","value":70},{"name":"Voolia","value":20}]},{"name":"Photospace","location":{"name":"Poland","code":"PL"},"partners":[{"name":"Yakitri","value":81},{"name":"Divavu","value":85},{"name":"Skimia","value":12},{"name":"Meeveo","value":27}]},{"name":"Realfire","location":{"name":"Poland","code":"PL"},"partners":[{"name":"Topicshots","value":81}]}]}; 
 

 
var countries = {}; 
 
jsondata.list.forEach(function (elem) { 
 
    if (elem.location.name in countries) { 
 
     countries[elem.location.name]++; 
 
    } else { 
 
     countries[elem.location.name] = 1; 
 
    } 
 
}); 
 

 
console.log(countries);

Answer 2

勧めします0 jsonとArray.reduceを使用してオブジェクトを取得します。

var companies = JSON.parse(json).list; //<-- unsafe for production 
var countries = companies.reduce(function(countries, company) { 
    var country = company.location.name; 
    if (typeof countries[country] === 'undefined' || countries[country] === null) { 
     countries[country] = 1; 
    } else { 
     countries[country]++; 
    } 

    return countries; 
}, {});