from
"data":[{"ja":"大阪市"},{"en":"Osaka"}]
I want to get "ja" and "en".
I tried several ways...
data.map(function(_, i) { return i; });
it returns array of numbers.
console.log(Object.keys(Object.values(data)));
all trials return
(2) [0, 1]
0: 0
1: 1
what can I do ?? please answer me. thank you.
Use map() and return the first key the object. You can get keys using Object.keys()
let data = [{"ja":"大阪市"},{"en":"Osaka"}]
let res = data.map(x => Object.keys(x)[0]);
console.log(res)If you don't want to use [0] use flatMap()
let data = [{"ja":"大阪市"},{"en":"Osaka"}]
let res = data.flatMap(x => Object.keys(x));
console.log(res)Note: The second method will also get the other properties other than first. For example
[{"ja":"大阪市","other":"value"},{"en":"Osaka"}] //["ja","other","en"];
let data = [{"ja":"大阪市"},{"en":"Osaka"}]
let res = data.reduce((arr, o) => {
return Object.keys(o).reduce((a, k) => {
if (a.indexOf(k) == -1) a.push(k);
return a;
}, arr)
}, []);
console.log(res);
data.map(x => Object.keys(x)[0])Bad JSON design though. Would make far more sense if both keys and values just belonged to the same object.[0]is that, as I stated, your JSON is badly designed.