如何转换 JavaScript hashmap？
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How to transform JavaScript hashmap?
提问by msqar
i'm trying to create a <String, Array()>map from a json object.
Imagine i got this json structure:
我正在尝试<String, Array()>从 json 对象创建地图。想象一下，我得到了这个 json 结构：
[
{
"userId": "123123",
"password": "fafafa",
"age": "21"
},
{
"userId": "321321",
"password": "nana123",
"age": "34"
}
]
The map i want to create would be:
我要创建的地图是：
key (string), value (array)
键（字符串），值（数组）
{
"userId": [
"123123",
"321321"
],
"password": [
"fafafa",
"nana123"
],
"age": [
"21",
"34"
]
}
Is it possible to do this? :/
是否有可能做到这一点？：/
Thanks in advance.
提前致谢。
回答by MrCode
var json = '[{"userId" : "123123", "password": "fafafa", "age": "21"}, {"userId" : "321321", "password" : "nana123", "age" : "34"}]';
var list = JSON.parse(json);
var output = {};
for(var i=0; i<list.length; i++)
{
for(var key in list[i])
{
if(list[i].hasOwnProperty(key))
{
if(typeof output[key] == 'undefined')
{
output[key] = [];
}
output[key].push(list[i][key]);
}
}
}
document.write(JSON.stringify(output));
Outputs:
输出：
{"userId":["123123","321321"],"password":["fafafa","nana123"],"age":["21","34"]}
{"userId":["123123","321321"],"password":["fafafa","nana123"],"age":["21","34"]}
回答by maerics
function mergeAttributes(arr) {
return arr.reduce(function(memo, obj) { // For each object in the input array.
Object.keys(obj).forEach(function(key) { // For each key in the object.
if (!(key in memo)) { memo[key] = []; } // Create an array the first time.
memo[key].push(obj[key]); // Add this property to the reduced object.
});
return memo;
}, {});
}
var json = '[{"userId" : "123123", "password": "fafafa", "age": "21"}, {"userId" : "321321", "password" : "nana123", "age" : "34"}]';
mergeAttributes(JSON.parse(json));
// {
// "userId": ["123123", "321321"],
// "password": ["fafafa", "nana123"],
// "age": ["21", "34"]
// }
回答by Binita Bharati
Javascript's JSON.stringify will help you to convert any JSON compliant object model into a JSON string.
Javascript 的 JSON.stringify 将帮助您将任何符合 JSON 的对象模型转换为 JSON 字符串。
