javascript：如何将最高层的json对象作为数组？

Question

With an array of objects in a form like this:

[
    { 
        1429={
            {
                8766={...},
                8483={...},
                7345={...}
            }
        }
    },
    {
        9041={...}
    }
]

how could i get back an array like this?: [1429, 9041]

If the array of objects would be in another structure this code would work:

var obj = {
    "5": "some",
    "8": "thing"
};
var keys = $.map(obj, function (value, key) {
    return key;
});

console.log(keys);

That would return [5, 8]. But in my example it just would return the indexes [0,1]

Even if I wouldn't know the depth of the object - is it possible to get the values on that level? I dont need the indexes, I need those values. I couldn't find anything about it so far. Any tips for me maybe?

PS: I know that i could work out something with these keys and a loop, but I'm just asking for a simplier way to do it.

Regards

Answer 1

you are looking for the keys in a json object, you can get them this way:

Object.keys(obj);

for the object example:

var obj = {
"5": "some",
"8": "thing"
};

you will get:

["5","8"]

for an array of object of this type:

var arrayObject = [{},{},{}]; 

you can use a map and get the keys:

var keys = arrayObject.map(function(k){
   return Object.keys(k);
});

keys is an array of arrays of keys. Example, for the following object (similar to your data structure):

var l= [
{ 
    1429:{

            8766: "test",
            8483:"test",
            7345: "test"

    }
},
{
    9041: "test"
}
];

you will get:

[["1429"],["9041"]]

apply concat and you will get what you are looking for. Here how to apply concat in the case of multiple arrays.

var arrayOfKeys = [].concat.apply([], keys);

now you will get:

["1429","9041"];

Answer 2

In your specific case you could use

var keys = [];
root.forEach(function(v) { keys = keys.concat(Object.keys(v)); });

If instead you have a tree of arrays and you want the keys of all other objects instead (but not recursing into objects) then a simple recursive function would do it:

function topKeys(x) {
   if (x && x.constructor === Array) {
       var result = [];
       x.forEach(function(item) {
           result = result.concat(topKeys(item));
       });
       return result;
   } else if (typeof x === "object") {
       return Object.keys(x);
   } else {
       return [];
   }
}