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Getting child data in a JavaScript object

I have been banging my head against this all night.
I have a service that is returning data that looks like this:
You will see there are Objects with a GUID, nested under a parent object. I need to loop through all the "GUID" objects and get the attributes (i.e., author, content, etc.).
The GUIDs are dynamic (I don't know what they are ahead of time). The attributes below it are known.
I am having trouble figuring out how to target it. I can't seem to successfully use a for or forEach loop on it.
I need to use native JavaScript (i.e. no jQuery for this one).

Here's a possible solution:
var keys = Object.keys(data);
var results =
keys.map(
function(key){
var datum = data[key];
// do whatever with the data.
return {
"author" : data["author"]
}
}
)
// now results is an array of {"author"} objects.

var x = {
'a-45-2455': {
'author': 'Some Name'
}
};
var keys = Object.keys(x);
keys.forEach(function(key,value){
var author = x[key]['author'];
console.log(author);
});
You can access the data in this way.
You can also create another array from the values and use that.

In order to loop through an object use for...in
Since you have not posted the code of object , here is a snippet with dummy object
var x = {
'a-45-2455': {
'author': 'Some Name'
}
}
for(var keys in x){
alert(x[keys].author)
}

If you are using angular try angular.forEach loop to iterate over all GUID's, else you can use for each in javascript. see below code snippet.
var user ={
'1': {
"name":'abc',
"age":26
},
'2': {
"name":'def',
"age":28
}
};
for(var key in user) {
console.log(user[key].name);
}

Here is another way to iterate through json Object
var obj = {a: 1, b: 2, c: {a: 1, b: 2}};
function walk(obj) {
for (var key in obj) {
if (obj.hasOwnProperty(key)) {
var val = obj[key];
console.log(val);
walk(val);
}
}
}
walk(obj);
var obj = {a: 1, b: 2, c: {a: 1, b: 2}};
function walk(obj) {
for (var key in obj) {
if (obj.hasOwnProperty(key)) {
var val = obj[key];
console.log(val);
walk(val);
}
}
}
walk(obj);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

I believe that you can iterate through all indexes using the advanced for loop. a.b is the same as a["b"] in javascript.

You can iterate thru the object properties like this:
for(let key in Response){
if(!Response.hasOwnProperty(key))
continue;
//key will be each GUID
let yourObject = Response[key] //Each object in the list of objects
}
You can read about for...in loops here
Hope that helps!

How to iterate through nested JSON values using asnyc.js

I'm relatively new to nodeJS/Javascript's asynchronous nature (Python background) and trying am trying to figure how to step through a nested JSON object, extract it's values using asnyc.js.
I came across this snippet, How to navigate in nested JSON.
function recursiveGetProperty(obj, lookup, callback) {
for (property in obj) {
if (property == lookup) {
callback(obj[property]);
} else if (obj[property] instanceof Object) {
recursiveGetProperty(obj[property], lookup, callback);
}
}
}
Which works great with this sample object, foo.
var foo = {
'key_1' : 'val1',
'key_2': {
'key_3': 'val3',
'key_4': 'val4'
}
}
recursiveGetProperty(foo, 'key_1', function(obj) {
console.log(obj);
});
returns 'val1'
recursiveGetProperty(foo, 'key_3', function(obj) {
console.log(obj);
});
returns 'val3'
This is exactly what I needed but when I feed it key values via iteration:
var keys = ['val1', 'val3'];
for (var keys in keys) {
recursiveGetProperty(foo, keys, function(obj) {
console.log(obj);
});
}
nothing is logged to console. so I wrote a logging function:
function log(obj) {
console.log(obj);
}
and tried:
for (var key in keys) {
recursiveGetProperty(foo, keys, log(obj));
}
but i get ReferenceError: obj is not defined.
I was told it's not a great idea to execute a callback inside a for loop, I'm not exactly sure why so I looked into async.js. It seems like the right solution for what I want but I have no idea how to go about it.
Using async.js, I would like to build a series of recursiveGetProperty functions, store them in an array, and then execute those calls asynchronously but I'm stumped on how to approach the problem.
What I would ultimately want is something like this:
async.each(['key_1', 'key_2', 'key_3'], recursiveGet(key) {
doSomethingWithData();
}, function(err) {
doSomethingWhenDone();
});
This would be used on an ExpressJS server to parse JSON and do something with it afterwards.
Any help or suggestion would be greatly appreciated.

There are bug in this code
var keys = ['val1', 'val3'];
for (var keys in keys) {
recursiveGetProperty(foo, keys, function(obj) {
console.log(obj);
});
}
The array of keys (line 1) is overwritten by the keys index (line 2) of the for loop. So let's rename that key.
For an iterated array a key would be a number (0, 1, ..., n), not a string. You need to use those numbers as indices to keys
Also your recursiveGetProperty finds by keys not values.
So the code should be
var keys = ['key_1', 'key_2'];
for (var key in keys) {
recursiveGetProperty(foo, keys[key], function(obj) {
console.log(obj);
});
}

var keys = ['key_1', 'key_2'];
keys.forEach(function (key) {
recursiveGetProperty(foo, key, function(obj) {
console.log(obj);
});
});
http://jsfiddle.net/fPRQK/
Issues in your code:
for(var key in obj) works with object properties only, not with array values. Use Array.forEach or a regular for loop instead.
recursiveGetProperty(foo, keys, log(obj)): This would call log instantly and pass it's return value to recursiveGetProperty. You could either pass just log or function (obj) { log(obj); }, which in this case mean the same. Also in this case what you want to pass is key.

javascript: How to get highest layer of json object as array?

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?
P.S.: 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

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"];

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 [];
}
}

Is array both associative and indexed?

Can an array in JavaScript be associative AND indexed?
I'd like to be able to lookup an item in the array by its position or a key value.

There are no such things as associative arrays in Javascript. You can use object literals, which look like associative arrays, but they have unordered properties. Regular Javascript arrays are based on integer indexes, and can't be associative.
For example, with this object:
var params = {
foo: 1,
bar: 0,
other: 2
};
You can access properties from the object, for example:
params["foo"];
And you can also iterate over the object using the for...in statement:
for(var v in params) {
//v is equal to the currently iterated property
}
However, there is no strict rule on the order of property iteration - two iterations of your object literal could return the properties in different orders.

After reading the Wikipedia definition of associative array, I'm going to break with traditional JavaScript lore and say, "yes, JavaScript does have associative arrays." With JavaScript arrays, you can add, reassign, remove, and lookup values by their keys (and the keys can be quoted strings), which is what Wikipedia says associative arrays should be able to do.
However, you seem to be asking something different--whether you can look up the same value by either index or key. That's not a requirement of associative arrays (see the Wikipedia article.) Associative arrays don't have to give you the ability to get a value by index.
JavaScript arrays are very closely akin to JavaScript objects.
arr=[];
arr[0]="zero";
arr[1]="one";
arr[2]="two";
arr["fancy"]="what?";
Yes, that's an array, and yes, you can get away with non-numeric indices. (If you're curious, after all this, arr.length is 3.)
In most cases, I think you should stick to numeric indices when you use arrays. That what most programmers expect, I think.
The link is to my blog post about the subject.

Native JS objects only accept strings as property names, which is true even for numeric array indices; arrays differ from vanilla objects only insofar as most JS implementations will store numerically indexed properties differently (ie in an actual array as long as they are dense) and setting them will trigger additional operations (eg adjustment of the length property).
If you're looking for a map which accepts arbitrary keys, you'll have to use a non-native implementation. The script is intended for fast iteration and not random-access by numeric indices, so it might nor be what you're looking for.
A barebones implementation of a map which would do what you're asking for could look like this:
function Map() {
this.length = 0;
this.store = {};
}
Map.prototype.get = function(key) {
return this.store.hasOwnProperty(key) ?
this.store[key] : undefined;
};
Map.prototype.put = function(key, value, index) {
if(arguments.length < 3) {
if(this.store.hasOwnProperty(key)) {
this.store[key].value = value;
return this;
}
index = this.length;
}
else if(index >>> 0 !== index || index >= 0xffffffff)
throw new Error('illegal index argument');
if(index >= this.length)
this.length = index + 1;
this[index] = this.store[key] =
{ index : index, key : key, value : value };
return this;
};
The index argument of put() is optional.
You can access the values in a map map either by key or index via
map.get('key').value
map[2].value

var myArray = Array();
myArray["first"] = "Object1";
myArray["second"] = "Object2";
myArray["third"] = "Object3";
Object.keys(myArray); // returns ["first", "second", "third"]
Object.keys(myArray).length; // returns 3
if you want the first element then you can use it like so:
myArray[Object.keys(myArray)[0]]; // returns "Object1"

The order in which objects appear in an associative javascript array is not defined, and will differ across different implementations. For that reason you can't really count on a given associative key to always be at the same index.
EDIT:
as Perspx points out, there aren't really true associative arrays in javascript. The statement foo["bar"] is just syntactic sugar for foo.bar
If you trust the browser to maintain the order of elements in an object, you could write a function
function valueForIndex(obj, index) {
var i = 0;
for (var key in obj) {
if (i++ == index)
return obj[key];
}
}

var stuff = [];
stuff[0] = "foo";
stuff.bar = stuff[0]; // stuff.bar can be stuff["bar"] if you prefer
var key = "bar";
alert(stuff[0] + ", " + stuff[key]); // shows "foo, foo"

I came here to wanting to know if this is bad practice or not, and instead found a lot of people appearing not to understand the question.
I wanted to have a data structure that was ordered but could be indexed by key, so that it wouldn't require iteration for every lookup.
In practical terms this is quite simple, but I still haven't read anything on whether it's a terrible practice or not.
var roygbiv = [];
var colour = { key : "red", hex : "#FF0000" };
roygbiv.push(colour);
roygbiv[colour.key] = colour;
...
console.log("Hex colours of the rainbow in order:");
for (var i = 0; i < roygbiv.length; i++) {
console.log(roygbiv[i].key + " is " + roygbiv[i].hex);
}
// input = "red";
console.log("Hex code of input colour:");
console.log(roygbiv[input].hex);
The important thing is to never change the value of array[index] or array[key] directly once the object is set up or the values will no longer match. If the array contains objects you can change the properties of those objects and you will be able to access the changed properties by either method.

Although I agree with the answers given you can actually accomplish what you are saying with getters and setters. For example:
var a = [1];
//This makes a["blah"] refer to a[0]
a.__defineGetter__("blah", function(){return this[0]});
//This makes a["blah"] = 5 actually store 5 into a[0]
a.__defineSetter__("blah", function(val){ this[0] = val});
alert(a["blah"]); // emits 1
a["blah"] = 5;
alert(a[0]); // emits 5
Is this what you are looking for? i think theres a different more modern way to do getters and setters but cant remember.

The tide has changed on this one. Now you can do that... and MORE! Using Harmony Proxies you could definitely solve this problem in many ways.
You'll have to verify that your targeted environments support this with maybe a little help from the harmony-reflect shim.
There's a really good example on the Mozilla Developer Network on using a Proxy to find an array item object by it's property which pretty much sums it up.
Here's my version:
var players = new Proxy(
[{
name: 'monkey',
score: 50
}, {
name: 'giraffe',
score: 100
}, {
name: 'pelican',
score: 150
}], {
get: function(obj, prop) {
if (prop in obj) {
// default behavior
return obj[prop];
}
if (typeof prop == 'string') {
if (prop == 'rank') {
return obj.sort(function(a, b) {
return a.score > b.score ? -1 : 1;
});
}
if (prop == 'revrank') {
return obj.sort(function(a, b) {
return a.score < b.score ? -1 : 1;
});
}
var winner;
var score = 0;
for (var i = 0; i < obj.length; i++) {
var player = obj[i];
if (player.name == prop) {
return player;
} else if (player.score > score) {
score = player.score;
winner = player;
}
}
if (prop == 'winner') {
return winner;
}
return;
}
}
});
console.log(players[0]); // { name: 'monkey', score: 50 }
console.log(players['monkey']); // { name: 'monkey', score: 50 }
console.log(players['zebra']); // undefined
console.log(players.rank); // [ { name: 'pelican', score: 150 },{ name: 'giraffe', score: 100 }, { name: 'monkey', score: 50 } ]
console.log(players.revrank); // [ { name: 'monkey', score: 50 },{ name: 'giraffe', score: 100 },{ name: 'pelican', score: 150 } ]
console.log(players.winner); // { name: 'pelican', score: 150 }

The latest MDN documentation makes it quiet clear that Array index must be integers.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
let arr=[];
arr[0]="zero";
arr[1]="one";
arr[2]="two";
arr["fancy"]="what?";
//Arrays cannot use strings as element indexes (as in an associative array) but must use integers.
//Setting non-integers using bracket notation will not set an element to the Array List itself
//A non-integer will set a variable associated with that ARRAY Object property collection
let denseKeys = [...arr.keys()];
console.log(denseKeys);//[ 0, 1, 2 ]
console.log("ARRAY Keys:"+denseKeys.length);//3
let sparseKeys = Object.keys(arr);
console.log(sparseKeys);//[ '0', '1', '2', 'fancy' ]
console.log("Object Keys:"+sparseKeys.length);//4
const iterator = arr.keys();
for (const key of iterator) {
console.log(key);//0,1,2
}

Yes.
test = new Array();
test[0] = 'yellow';
test['banana'] = 0;
alert(test[test['banana']]);

Getting the first index of an object

Consider:
var object = {
foo: {},
bar: {},
baz: {}
}
How would I do this:
var first = object[0];
console.log(first);
Obviously, that doesn’t work because the first index is named foo,
not 0.
console.log(object['foo']);
works, but I don’t know it’s named foo. It could be named anything. I just want the first.

Just for fun this works in JS 1.8.5
var obj = {a: 1, b: 2, c: 3};
Object.keys(obj)[0]; // "a"
This matches the same order that you would see doing
for (o in obj) { ... }

If you want something concise try:
for (first in obj) break;
alert(first);
wrapped as a function:
function first(obj) {
for (var a in obj) return a;
}

they're not really ordered, but you can do:
var first;
for (var i in obj) {
if (obj.hasOwnProperty(i) && typeof(i) !== 'function') {
first = obj[i];
break;
}
}
the .hasOwnProperty() is important to ignore prototyped objects.

This will not give you the first one as javascript objects are unordered, however this is fine in some cases.
myObject[Object.keys(myObject)[0]]

If the order of the objects is significant, you should revise your JSON schema to store the objects in an array:
[
{"name":"foo", ...},
{"name":"bar", ...},
{"name":"baz", ...}
]
or maybe:
[
["foo", {}],
["bar", {}],
["baz", {}]
]
As Ben Alpert points out, properties of Javascript objects are unordered, and your code is broken if you expect them to enumerate in the same order that they are specified in the object literal—there is no "first" property.

for first key of object you can use
console.log(Object.keys(object)[0]);//print key's name
for value
console.log(object[Object.keys(object)[0]]);//print key's value

There is no way to get the first element, seeing as "hashes" (objects) in JavaScript have unordered properties. Your best bet is to store the keys in an array:
var keys = ["foo", "bar", "baz"];
Then use that to get the proper value:
object[keys[0]]

ES6
const [first] = Object.keys(obj)

Using underscore you can use _.pairs to get the first object entry as a key value pair as follows:
_.pairs(obj)[0]
Then the key would be available with a further [0] subscript, the value with [1]

I had the same problem yesterday. I solved it like this:
var obj = {
foo:{},
bar:{},
baz:{}
},
first = null,
key = null;
for (var key in obj) {
first = obj[key];
if(typeof(first) !== 'function') {
break;
}
}
// first is the first enumerated property, and key it's corresponding key.
Not the most elegant solution, and I am pretty sure that it may yield different results in different browsers (i.e. the specs says that enumeration is not required to enumerate the properties in the same order as they were defined). However, I only had a single property in my object so that was a non-issue. I just needed the first key.

You could do something like this:
var object = {
foo:{a:'first'},
bar:{},
baz:{}
}
function getAttributeByIndex(obj, index){
var i = 0;
for (var attr in obj){
if (index === i){
return obj[attr];
}
i++;
}
return null;
}
var first = getAttributeByIndex(object, 0); // returns the value of the
// first (0 index) attribute
// of the object ( {a:'first'} )

To get the first key of your object
const myObject = {
'foo1': { name: 'myNam1' },
'foo2': { name: 'myNam2' }
}
const result = Object.keys(myObject)[0];
// result will return 'foo1'

Based on CMS answer. I don't get the value directly, instead I take the key at its index and use this to get the value:
Object.keyAt = function(obj, index) {
var i = 0;
for (var key in obj) {
if ((index || 0) === i++) return key;
}
};
var obj = {
foo: '1st',
bar: '2nd',
baz: '3rd'
};
var key = Object.keyAt(obj, 1);
var val = obj[key];
console.log(key); // => 'bar'
console.log(val); // => '2nd'

My solution:
Object.prototype.__index = function(index)
{
var i = -1;
for (var key in this)
{
if (this.hasOwnProperty(key) && typeof(this[key])!=='function')
++i;
if (i >= index)
return this[key];
}
return null;
}
aObj = {'jack':3, 'peter':4, '5':'col', 'kk':function(){alert('hell');}, 'till':'ding'};
alert(aObj.__index(4));