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Recursive function in javascript that outputs JSON

In plain javascript, I am trying to create a function that will return a tree structure (json) of a folder, its subfolders and any files. I'm trying to achieve this using recursion.
The problem with the below code is that it stops after the first recursive call.
I know that in JS you do references, and I need to create a new object that I pass the values from the previous call to, but I am struggling to do so.
function fun(file, json) {
var tempJson = {
'name' : json.name || '',
'children' : obj.children || new Object()
};
if (file.type == 'file') {
tempJson.type = 'file';
tempJson.children = {}; // this will be empty, since there are no children
}
else {
tempJson.type = 'dir';
var listed = file.listFiles();
if (listed.length > 0) {
for each (var item in listed) {
tempJson.children = fun(item, tempJson);
}
} else {
tempJson.children = {};
}
}
return tempJson;
}
Example
From a directory structure like:
-root
--file1
--dir1
---file1.1
--dir2
I would like to get a json like:
{
name: 'root',
type: 'dir',
children : [
{
name: 'file1',
type: 'file',
children: {}
},
{
name: 'dir1',
type: 'dir',
children:
{
name: 'file1.1',
type: 'file',
children: {},
}
},
name: 'dir2',
type: 'dir',
children: {}
}
First call:
var object = new Object();
fun(rootdir, object);
Hope this makes sense.
Thanks!

As pointed out in the comments, children should be an array:
function fun(entry) {
var entryObj = { // construct the object for this entry
name: entry.name || "",
type: entry.type, // put the type here instead of using an if
children: [] // children must be an array
};
if(entry.type === "dir") { // if this entry is a directory
var childEntries = entry.listFiles(); // get its child entries
for(var childEntry of childEntries) { // and for each one of them
entryObj.children.push(fun(childEntry)); // add the result of the call of 'fun' on them to the children array
}
}
return entryObj;
}
Then call it like so:
var tree = fun(rootEntry);

Update fields in nested objects in Typescript / Javascript

In Firestore you can update fields in nested objects by a dot notation (https://firebase.google.com/docs/firestore/manage-data/add-data?authuser=0#update_fields_in_nested_objects). I wonder how to make that work in Typescript / Javascript.
For example the following object:
const user = {
id: 1
details: {
name: 'Max',
street: 'Examplestreet 38',
email: {
address: 'max#example.com',
verified: true
}
},
token: {
custom: 'safghhattgaggsa',
public: 'fsavvsadgga'
}
}
How can I update this object with the following changes:
details.email.verified = false;
token.custom = 'kka';
I already found that Lodash has a set function:
_.set(user, 'details.email.verified', false);
Disadvantage: I have to do this for every change. Is their already a method to update the object with an object (like firestore did)?
const newUser = ANYFUNCTION(user, {
'details.email.verified': false,
'token.custom' = 'kka'
});
// OUTPUT for newUser would be
{
id: 1
details: {
name: 'Max',
street: 'Examplestreet 38',
email: {
address: 'max#example.com',
verified: false
}
},
token: {
custom: 'kka',
public: 'fsavvsadgga'
}
}
Does anyone know an good solution for this? I already found more solutions if I only want to change one field (Dynamically set property of nested object), but no solution for more than one field with one method

I think you are stuck with using a function but you could write it yourself. No need for a lib:
function set(obj, path, value) {
let parts = path.split(".");
let last = parts.pop();
let lastObj = parts.reduce((acc, cur) => acc[cur], obj);
lastObj[last] = value;
}
set(user, 'details.email.verified', false);
if what you want to do is merge 2 objects then it is a bit trickier:
function forEach(target, fn) {
const keys = Object.keys(target);
let i = -1;
while (++i < keys.length) {
fn(target[keys[i]], keys[i]);
}
}
function setValues(obj, src) {
forEach(src, (value, key) => {
if (value !== null && typeof (value) === "object") {
setValues(obj[key], value);
} else {
obj[key] = value;
}
});
}
let obj1 = {foo: {bar: 1, boo: {zot: null}}};
let obj2 = {foo: {baz: 3, boo: {zot: 5}}};
setValues(obj1, obj2);
console.log(JSON.stringify(obj1));

One solution in combination with lodash _.set method could be:
function setObject(obj, paths) {
for (const p of Object.keys(paths)) {
obj = _.set(obj, p, paths[p]);
}
return obj;
}

Return object with subset of its attributes

I've got a flat JavaScript object like this:
{
id: 3726492,
kind: 'user',
permalink: 'nicholas',
username: 'Nicholas',
...
a lot more attributes
}
I'd like to create a new object which only has a subset of the attributes of the original object.
Something like
var newObject = oldObject.fields(['id', 'username']);
newObject would be
{
id: 3726492,
username: 'Nicholas'
}
Is there already something like this?

Try this
function pick(data, keys) {
var result = {};
keys.forEach(function (key) {
if (data.hasOwnProperty(key)) {
result[key] = data[key];
}
});
return result;
}
var data = {
id: 3726492,
kind: 'user',
permalink: 'nicholas',
username: 'Nicholas'
}
var newData = pick(data, ['id', 'kind']);
console.log(newData);
In underscorejs or lodash there is method .pick
var data = {
id: 3726492,
kind: 'user',
permalink: 'nicholas',
username: 'Nicholas',
};
var newObject = _.pick(data, 'id', 'username');
console.log(newObject);
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>

You can use Array.prototype.reduce to reduce one object to another using the list of properties:
function subset(obj, propList) {
return propList.reduce(function(newObj, prop) {
obj.hasOwnProperty(prop) && (newObj[prop] = obj[prop]);
return newObj;
}, {});
}
var obj = {
id: 3726492,
kind: 'user',
permalink: 'nicholas',
username: 'Nicholas'
};
var newObj = subset(obj, ['id', 'username']);
console.log(newObj);
document.getElementById('json').innerText = JSON.stringify(newObj);
<pre id="json"></pre>

Not built-in, but you can sure define a simple function that does the job:
var original = {a:1112, b:434, c:666, d:222};
function fieldSubset(obj, fields) {
var subsetClone = {};
for( var i=0,l=fields.length; i<l; i++) {
// This can prevent filling undefined as properties
if(obj.hasOwnProperty(fields[i])) {
subsetClone[fields[i]] = obj[fields[i]];
}
}
return subsetClone;
}
fieldSubset(original, ["a", "c"]);
You can also use this in Object.prototype, but be aware that this might happen to conflict with native API in the future versions of JavaScript:
var original = {a:1112, b:434, c:666, d:222};
Object.defineProperty(Object.prototype, "fieldSubset", {
value: function(fields) {
var subsetClone = {};
for( var i=0,l=fields.length; i<l; i++) {
// This can prevent filling undefined as properties
if(this.hasOwnProperty(fields[i])) {
subsetClone[fields[i]] = this[fields[i]];
}
}
return subsetClone;
},
enumerable: false,
configurable: true}
);
original.fieldSubset(["a", "c"]);

One liner using Array.prototype.reduce. We are also using Object.assign. The idea is to keep extending a blank object with the keys found in the filters array. If you see, the reduce function takes a callback function with arg1,arg2,arg3 params as the first argument and an empty object as the second argument. This object will be cloned and extended with the help of the keys specified in the filters array.
var a = {
id: 3726492,
kind: 'user',
permalink: 'nicholas',
username: 'Nicholas',
};
var filters = ["id","username","permalink"];
var sub = Object.keys(a).reduce((arg1,arg2,arg3)=>{ var res = {}; if(filters.indexOf(arg2)>=0){ res[arg2] = a[arg2]; } return Object.assign(arg1,res);},{})
console.log(sub);

You haven't specifically mentioned what is the type of values behind your object's keys. Your current answers cover the shallow copy and deep copy.
Another alternative would be to create a view of the original object. This would be helpful if you have very large data objects and you do not want them copy in the memory.
function View(obj, properties) {
var view = {};
properties.forEach(function(prop) {
Object.defineProperty(view, prop, {
get: function() {
return obj[prop];
},
set: function(val) {
obj[prop] = val;
},
enumerable: true,
configurable: true
});
});
return view;
}
then with your data you can do:
var data = {
id: 3726492,
kind: 'user',
permalink: 'nicholas',
username: 'Nicholas',
},
view = new View(data, ['id', 'username']);
view.id; // 3736492
view.username; // Nicholas
of course you have to be aware that you can change your original object just by view.id = 'something else'. However it is easily preventable.

Reordering array objects via javascript

I have been doing some sorting and still dont get it why the result is []. could you guys help me out what im missing?
I have my raw array object:
var data = [
{message:'hello', username:'user1'},
{message:'data', username:'user1'},
{message:'sample', username:'user2'},
{message:'here', username:'user2'},
];
my function is:
var chat = [];
function reorder(obj) {
obj.forEach( function(val, i) {
if(typeof chat[val.username] === 'undefined') {
chat[val.username] = [];
chat[val.username].push(val);
}
else
chat[val.username].push(val);
});
return chat;
}
and on my console:
reorder(data);
I am expecting to have:
var data2 = [
'user1': [{message:'hello', username:'user1'}, {message:'data', username:'user1'} ],
'user2': [{message:'sample', username:'user2'}, {message:'here', username:'user2'} ],
];

You can do this easily with reduce:
var data2 = data.reduce(function(acc, x) {
acc[x.username] = (acc[x.username] || []).concat(x)
return acc
},{})
/*^
{ user1:
[ { message: 'hello', username: 'user1' },
{ message: 'data', username: 'user1' } ],
user2:
[ { message: 'sample', username: 'user2' },
{ message: 'here', username: 'user2' } ] }
*/

The problem is that you made chat an array. When you look at an array in the console, it only displays the numeric indexes, not the named properties; you have to use console.log(chat) to see the named properties.
Since you want this to be an object with named properties, you should declare it as an object, not an array:
var chat = {};

Use Underscore's _.groupBy:
_.groupBy(data, 'username')

In mongoose how to iterate over array of ObjectId?

I try to refactor from javascript object to mongoose object.
I have two simple models:
Candidate model:
var candidateSchema = new Schema({
name: String,
score: { type: Number, default: 0, min: -2, max: 2 }
});
candidateSchema.methods.updateScore = function updateScore(newScore) {
this.score = newScore;
};
Vote model containing a list of candidate:
var voteSchema = new Schema({
candidates: [
{ type: Schema.Types.ObjectId, ref: 'Candidate' }
]
});
function candidateAlreadyExists(candidates, newCandidate) {
var alreadyExists = false;
candidates.forEach(function (candidate) {
if (newCandidate.name === candidate.name) {
alreadyExists = true;
}
});
return alreadyExists;
}
voteSchema.methods.addCandidate = function addCandidate(newCandidate, callback) {
var candidates = this.candidates;
if (!candidateAlreadyExists(candidates, newCandidate)) {
candidates.push(newCandidate);
}
this.save(callback);
};
I try to add a static method in my voteSchema to add a new candidate, only if it doesn't exist.
I can't iterate over my candidates (candidates.forEach(function (candidate) {) because it's an array of _ids and not an array of javascript objects
Someone have an idea ?

It would be better to use $addToSet to let MongoDB do that for you atomically.
voteSchema.methods.addCandidate = function addCandidate(newCandidate, callback) {
this.candidates.addToSet(newCandidate._id);
this.save(callback);
};