从 JSON 文件获取特定键/值对的数组

Question

初学者 - 我想从 JSON 文件为我的世界城市类型提前项目创建一个数组。我已经获取了数据，现在我想提取 2 个键/值对（称为名称/国家/地区）并将它们推送到一个新的字符串数组中，该数组的语法如下：const arr = ["name, country", "name, country", "name, country"...]以下是数据示例：[]:0: {country: "Andorra", geonameid: 3040051, name: "les Escaldes", subcountry: "Escaldes-Engordany"}1: {country: "Andorra", geonameid: 3041563, name: "Andorra la Vella", subcountry: "Andorra la Vella"}2: {country: "United Arab Emirates", geonameid: 290594, name: "Umm al Qaywayn", subcountry: "Umm al Qaywayn"}3: {country: "United Arab Emirates", geonameid: 291074, name: "Ras al-Khaimah", subcountry: "Raʼs al Khaymah"}...我知道我必须使用.push()and.forEach()或 for 循环，但我不知道如何去做。谁能告诉我怎么做？

Answer 1

map像这样使用：

const arr = data.map(city => city.name + ", " + city.country);

arrdata将是一个与 in中的每个city对象data映射到 string 的长度相同的新数组city.name + ", " + city.country。

演示：

const data = [ {country: "Andorra", geonameid: 3040051, name: "les Escaldes", subcountry: "Escaldes-Engordany"}, {country: "Andorra", geonameid: 3041563, name: "Andorra la Vella", subcountry: "Andorra la Vella"}, {country: "United Arab Emirates", geonameid: 290594, name: "Umm al Qaywayn", subcountry: "Umm al Qaywayn"}, {country: "United Arab Emirates", geonameid: 291074, name: "Ras al-Khaimah", subcountry: "Raʼs al Khaymah"} ];

const arr = data.map(city => city.name + ", " + city.country);

console.log(arr);

Answer 2

const data = [{country: "Andorra", geonameid: 3040051, name: "les Escaldes", subcountry: "Escaldes-Engordany"},

{country: "Andorra", geonameid: 3041563, name: "Andorra la Vella", subcountry: "Andorra la Vella"},

{country: "United Arab Emirates", geonameid: 290594, name: "Umm al Qaywayn", subcountry: "Umm al Qaywayn"},

{country: "United Arab Emirates", geonameid: 291074, name: "Ras al-Khaimah", subcountry: "Raʼs al Khaymah"}]

const arr = data.map(i => `${i.name} , ${i.country}`);

console.log(arr)

Answer 3

forEach 的简单解决方案

countries = [

  {country: "Andorra", geonameid: 3040051, name: "les Escaldes", subcountry: "Escaldes-Engordany"},

  {country: "Andorra", geonameid: 3041563, name: "Andorra la Vella", subcountry: "Andorra la Vella"},

  {country: "United Arab Emirates", geonameid: 290594, name: "Umm al Qaywayn", subcountry: "Umm al Qaywayn"},

  {country: "United Arab Emirates", geonameid: 291074, name: "Ras al-Khaimah", subcountry: "Raʼs al Khaymah"}

]

let arr = [];

let result = [];

countries.forEach((country, index) => {

    let nameStr = `${country.name}, ${country.country}`

    result.push(nameStr);

})

console.log(result)

//output

//["les Escaldes Andorra", "Andorra la Vella Andorra", "Umm al Qaywayn United Arab Emirates", "Ras al-Khaimah United Arab Emirates"]

Answer 4

如果您愿意，可以使用reduce函数：

arr.reduce((acc, curr) => [...acc, (`${curr.name}, ${curr.country}`)], []);

它将以您想要的格式返回您的值。

下面的例子。

const arr = [

    {country: 'Andorra', geonameid: 3040051, name: 'les 1', subcountry: 'Escaldes-Engordany'},

    {country: 'Turkey', geonameid: 3040021, name: 'les Escaldes', subcountry: 'aaaa'},

    {country: 'IDK', geonameid: 3040021, name: 'Wow', subcountry: 'aaaa'}

];

const custom = arr.reduce((acc, curr) => [...acc, (`${curr.name}, ${curr.country}`)], []);

console.log(custom);