在循環中創建對象

我有一個公司和國家的json文件。創建對象的最正確方法是什麼？循環遍歷所有國家，我必須計算有多少公司與某個特定國家相關，以便獲得結果對象，大致採用以下格式：在循環中創建對象

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

來源

2017-09-02 Дмитрий Моисеев

'變種國家= {};'，然後使用'國家[國家名稱] =（國家[國家名稱] || 0）+ 1添加國家循環內的對象;' – 4castle

可以添加例如JSON ？我們理解結構的最小量。是不是像：'[{...}，...]'？ – christo8989

json文件，你可以在這裏找到http://codeit.pro/frontTestTask/company/getList –

你可以嘗試這樣的事情：（使用你在你的問題有編輯前的對象數據。）

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);

來源

2017-09-02 15:23:31 Ivar

你有使用'map'而不是'reduce'的原因嗎？我覺得這個問題更適合「減少」。 – christo8989

@ christo8989那麼最初的想法是我將值映射到數組中的新值，但想到它，它並沒有做更多的事情，只是循環遍歷每個元素......我只是將它更改爲的forEach。 – Ivar

你會想JSON.parse json並使用Array.reduce來獲取你的對象。

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; 
}, {});

來源

2017-09-02 15:27:02 christo8989

在循環中創建對象

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