How to extract json Response? - json

Question

Someone told me.
obj is a JSON response.
obj =　{ title: 'ABCD', _key: '-KX9Cwwuc2FjxcG-SNY0' }
I can get ABCD using console.log(obj["title”]).
How about complex case?
obj = { '-KXu3irrOjUtcejm4VF3':
{ gold: 0,
title: ‘xxxx09x#gmail.com',
uketuke: 0,
user: ‘xxxx09x#gmail.com' },
'-KXu3vLo7--JeVYC9fJa': { title: ‘JUMP' },
'-KXu3yRZgFlDcS8BZ7e1': { title: 'JUMP1' } }
In this case, how can I get the user entity?
By the way like this obj["title”] presentation, I think this should be ECMA standard,
please let me know where reference is?

Answer 1

If you knew the key then it's quite easy. For example:
obj = {
'-KXu3irrOjUtcejm4VF3': {
gold: 0,
title: 'xxxx09x#gmail.com',
uketuke: 0,
user: 'xxxx09x#gmail.com'
},
'-KXu3vLo7--JeVYC9fJa': { title: 'JUMP' },
'-KXu3yRZgFlDcS8BZ7e1': { title: 'JUMP1' }
}
var user_key = '-KXu3irrOjUtcejm4VF3'
user = obj[user_key].user
"xxxx09x#gmail.com"
However if you did not know the key of object in which the user exists then the following function can help with asymptotic complexity O(n):
function getUser(obj) {
for (var key in obj) {
// skip loop if the property is from prototype
if (!obj.hasOwnProperty(key)) continue;
if (typeof obj[key].user !== undefined) {
return obj[key].user;
}
}
}
getUser(obj)
"xxxx09x#gmail.com"
And finally there is something I used in one of projects: jsonpath
$..user
would return all user from your obj. This way you can go quite far with a complicated json IMHO.

Answer 2

Need to do some corrections :
To access the property value from this JSON response var obj =　{ title: 'ABCD', _key: '-KX9Cwwuc2FjxcG-SNY0' } you have to use dot(.) operator instead of [].
If you will use obj[title] it will give you an error :
Uncaught ReferenceError: title is not defined(…)
If you will use obj.title it will give you an output :
ABCD
So, as per the complex case :
First thing : Strings should be wrapped in double quotes.
Invalid JSON :
var obj = {
'-KXu3irrOjUtcejm4VF3': {
gold: 0,
title: 'xxxx09x#gmail.com',
uketuke: 0,
user: 'xxxx09x#gmail.com'
},
'-KXu3vLo7--JeVYC9fJa': { title: ‘JUMP' },
'-KXu3yRZgFlDcS8BZ7e1': { title: 'JUMP1' }
};
Valid JSON :
var obj = {
"-KXu3irrOjUtcejm4VF3": {
"gold": 0,
"title": "abc#gmail.com",
"uketuke": 0,
"user": "def#gmail.com"
},
"-KXu3vLo7--JeVYC9fJa": {
"title": "JUMP"
},
"-KXu3yRZgFlDcS8BZ7e1": {
"title": "JUMP1"
}
}