我有一个这样的 json 文件:
[
{
"countryName": "Austria",
"countryID": "AT",
"countryPopulation": 8451860,
"regions":[
{
"regionName": "Burgenland (AT)",
"regionID": "AT11",
"regionPopulation": 286691
},
{
"regionName": "Niederösterreich",
"regionID": "AT12",
"regionPopulation": 1618592
},
{
"regionName": "Wien",
"regionID": "AT13",
"regionPopulation": 1741246
},
{
"regionName": "Kärnten",
"regionID": "AT21",
"regionPopulation": 555473
},
{
"regionName": "Steiermark",
"regionID": "AT22",
"regionPopulation": 1210971
},
{
"regionName": "Oberösterreich",
"regionID": "AT31",
"regionPopulation": 1418498
},
{
"regionName": "Salzburg",
"regionID": "AT32",
"regionPopulation": 531898
},
{
"regionName": "Tirol",
"regionID": "AT33",
"regionPopulation": 715888
},
{
"regionName": "Vorarlberg",
"regionID": "AT34",
"regionPopulation": 372603
}
]
},
{
"countryName": "Belgium",
"countryID": "BE",
"countryPopulation": 11161642,
"regions":[
{
"regionName": "Région de Bruxelles-Capitale",
"regionID": "BE10",
"regionPopulation": 1174624
},
{
"regionName": "Prov. Antwerpen",
"regionID": "BE21",
"regionPopulation": 1802309
},
{
"regionName": "Prov. Limburg (BE)",
"regionID": "BE22",
"regionPopulation": 855963
},
{
"regionName": "Prov. Oost-Vlaanderen",
"regionID": "BE23",
"regionPopulation": 1465150
},
{
"regionName": "Prov. Vlaams-Brabant",
"regionID": "BE24",
"regionPopulation": 1103737
},
{
"regionName": "Prov. West-Vlaanderen",
"regionID": "BE25",
"regionPopulation": 1177567
},
{
"regionName": "Prov. Brabant Wallon",
"regionID": "BE31",
"regionPopulation": 389479
},
{
"regionName": "Prov. Hainaut",
"regionID": "BE32",
"regionPopulation": 1332489
},
{
"regionName": "Prov. Liège",
"regionID": "BE33",
"regionPopulation": 1095977
},
{
"regionName": "Prov. Luxembourg (BE)",
"regionID": "BE34",
"regionPopulation": 278278
},
{
"regionName": "Prov. Namur",
"regionID": "BE35",
"regionPopulation": 486069
}
]
},
{
"countryName": "Bulgaria",
"countryID": "BG",
"countryPopulation": 7284552,
"regions":[
{
"regionName": "Severozapaden",
"regionID": "BG31",
"regionPopulation": 823469
},
{
"regionName": "Severen tsentralen",
"regionID": "BG32",
"regionPopulation": 844511
},
{
"regionName": "Severoiztochen",
"regionID": "BG33",
"regionPopulation": 957460
},
{
"regionName": "Yugoiztochen",
"regionID": "BG34",
"regionPopulation": 1067981
},
{
"regionName": "Yugozapaden",
"regionID": "BG41",
"regionPopulation": 2128783
},
{
"regionName": "Yuzhen tsentralen",
"regionID": "BG42",
"regionPopulation": 1462348
}
]
},
...
然后我有两个变量:cs 和rs。在任何时刻，只有其中一个不同于 null。
cs 包含用户选择的国家，rs 包含用户选择的地区。
如前所述，如果 cs 不同于 null，则 rs 为 null，反之亦然。
这是因为用户可以从 map 中选择一个国家或选择一个国家的地区。
我的目标是创建一个复选框(或类似的东西，我仍然需要考虑)，允许您选择当前地区(国家)之外的其他地区(国家)，以便您可以比较数据。
我想要的是:
if
cs != null-> 我想获取国家列表(Json 文件中的所有国家)if
rs != null-> 我想获取 rs 所属国家/地区的区域列表。
为了更好地了解彼此:
这就是我尝试做的。
// global variables
cs = null; // if it is not null, the user has selected this country
csi = null; // country id
rs = null; // if it is not null, the user has selected this region
rsi = null; // region id
currentCountries = null; // list of all countries
currentRegions = null; // list of regions in the selected country
/**
* Function that creates line charts only when a country or a region is clicked.
*/
function createLineChart(antigenSelected, yearSelected, countrySelected, countrySelectedId, regionSelected, regionSelectedId) {
defineLines(antigenSelected, yearSelected, countrySelected, countrySelectedId, regionSelected, regionSelectedId);
}
function defineLines(antigenSelected, yearSelected, countrySelected, countrySelectedId, regionSelected, regionSelectedId) {
/**
* To know if the user has clicked on the country or region, check that the selected region belongs to the selected country:
* - if it belongs to us -> the user has clicked on the selected region
* - if it does not belong to us -> the user has clicked on the selected country.
* At any moment only one of the two possibilities is assigned (the other is null).
*/
cs = null; // if it is not null, the user has selected this country
csi = null; // country id
rs = null; // if it is not null, the user has selected this region
rsi = null; // region id
// if the user has selected a region
if(regionSelectedId != null && countrySelectedId == regionSelectedId.substring(0, 2)) {
rs = regionSelected;
rsi = regionSelectedId;
}
// if the user has selected a country
else {
cs = countrySelected;
csi = countrySelectedId;
}
console.log("countrySelected: " + cs);
console.log("regionSelected: " + rs);
/**
* Load json with countries and regions.
*/
d3.json("../Project2/data/json/countriesAndRegions.json", function(error, countriesAndRegions) {
if(error) {
console.log("*** ERROR LOADING FILES: " + error + " ***");
throw error;
}
countriesAndRegions.forEach(function(c) {
allCountries.push(c.countryName);
currentRegions = c.regions;
});
currentRegions.forEach(function(r) {
//console.log(r.regionName);
});
console.log(allCountries);
console.log(currentRegions);
//var nested = d3.nest()
// I have to nest data?
//.object(currentRegions);
});
}
显然这段代码不起作用。或者更确切地说，它适用于 allCountries 但不适用于 currentRegions。
我该如何解决？我应该使用 nest() 方法吗？
我想要的是:
- if
cs != null-> 获取所有国家 - if
rs != null-> 获取rs区域所属国家/地区的所有区域。
非常感谢
为了简化，假设我有这个 json 文件。
var users = [
{
name: 'Corbin',
age: 20,
favoriteFoods: ['ice cream', 'pizza'],
other: [
{
a: 12,
b: "apple"
},
{
a: 15,
b: "pear"
}
]
},
{
name: 'John',
age: 25,
favoriteFoods: ['ice cream', 'skittle'],
other: [
{
a: 0,
b: "cinnamon"
},
{
a: 854,
b: "ginger"
},
{
a: 24,
b: "salt"
}
]
}
];
然后我有一个包含字符串 ginger 的变量。如何获取列表 [cinnamon, ginger, salt]？
如果我有一个包含字符串 Corbin 的变量，我该如何获取列表 [Corbin, John]？
最佳答案
例如，我有一个与您的 json 数组相同的 json 数组示例:
var users = [{name: 'Corbin', age: 20, favoriteFoods: ['ice cream', 'pizza']},
{name: 'John', age: 25, favoriteFoods: ['ice cream', 'skittle']}];
我必须访问第二个用户的年龄属性，然后:
users[1].age 将起作用。
如果您必须访问第一个用户的第二个“favoriteFood”，那么您应该使用:
用户[0].favoriteFoods[2]。
根据您的要求，我将发布另一个示例代码:
关于javascript - 从 JSON 获取信息，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48094513/