Develop Reference

How to convert a method to recursive function in Javascript?

I created a submenu from the first keys of the "res" data before the dot. In this submenu, I showed the keys with the same name in the "res" data only once. ie: "user", "department" and "project" appear as just a submenu item. But when I click on them, other keys with the same name do not appear once. For example: When I click on the "project" item, 5 "type" submenus are opened. And I need to do the same for the "id" key, too. How can I solve this?
var res = {
"user.name.firstname": "firstname",
"user.name.lastname": "lastname",
"department.id1": 1,
"department.id2": 2,
"project.name": "project",
"project.type.name": "project1",
"project.type.id.first3": "321",
"project.type.id.last3" : "789",
"project.type.id.abc": "abc",
}
var myList = []
var myFinalList = []
Object.keys(res).forEach(key => {
var subMenus = key.split(".")
subMenus.forEach(subMenu => {
var newObject = {}
newObject["id"] = subMenu
newObject["content"] = subMenu
myList.push(newObject)
})
for (var i = myList.length - 1; i >= 0; i--) {
if (i - 1 !== -1) {
//console.log(i - 1)
myList[i - 1]["submenu"] = [myList[i]]
}
}
myFinalList.push(myList[0])
//console.log(myList)
myList = []
})
var mySet = new Set()
myFinalList.forEach(obj => {
mySet.add(obj["id"])
})
var veryFinalList = []
mySet.forEach(key => {
var eachKeyObject = myFinalList.filter(sub => sub.id === key)
var sourceObject = eachKeyObject[0]
if(eachKeyObject.length > 1){
for(var i = 1; i < eachKeyObject.length; i++){
sourceObject["submenu"] = sourceObject["submenu"].concat(eachKeyObject[i]["submenu"])
}
}
veryFinalList.push(sourceObject)
console.log(veryFinalList)
})
And my output should be like this:
output= {
"user": {
"name": {
"firstname": "firstname",
"lastname": "lastname",
}
},
"department": {
"id1":1,
"id2":2,
},
"project": {
"name": "project",
"type": {
"name": "project1",
"id": {
"first3": "321",
"last3" : "789",
"abc" : "abc"
}
}
}
}

Here you go:
var res = {
"user.name.firstname": "firstname",
"user.name.lastname": "lastname",
"department.id1": 1,
"department.id2": 2,
"project.name": "project",
"project.type.name": "project1",
"project.type.id.first3": "321",
"project.type.id.last3" : "789",
"project.type.id.abc": "abc",
}
let finalObj = { };
for(let key in res) {
let value = res[key];
let keyArr = key.split('.');
// Magic happens here (https://stackoverflow.com/a/68860247/2284136)
keyArr.reduce((acc, key, i) => {
if (i < keyArr.length - 1) {
if (!acc[key]) acc[key] = {};
}
else {
acc[key] = value;
}
return acc[key];
}, finalObj)
}
console.log(finalObj);
I used this answer for the reduce implementation, which allows us to put data deep into an object path. We just have to split the keys into and array first, like "user.name.firstname" => ["user", "name", "firstname"] and feed that to the reduce function with the value of res["user.name.firstname"].
Regarding your actual question about "converting a method to recursive function", I did try something like that at first, until I realized we don't need to do that here.
Also for a future reference, while recursive functions are great for some specific problems, the rule of thumb in general is to avoid having to use them if you don't absolutely have to. They are hard to read and understand, hard to debug and can lead to all kinds of wacky problems.
And regarding what you had tried to do to solve this. I think it's a great try and that is exactly what a great programmer should do when running into trouble! I love reading code like that because I can see the rabbit hole of frustration you were digging yourself into when trying to solve the problem. While it is indeed greatly frustrating, it also just as great learning experience. I personally think that when you find yourself from the bottom of that hole, still without a solution, that is the best time to ask for help, like you did!

How to filter out objects if two keys are duplicate

const obj =
[
{
"id":"1",
"name":"a",
"email":"abc#gmail.com",
"expiryType":"premium"
},
{
"id":"2",
"name":"b",
"email":"abc#gmail.com",
"expiryType":"gold"
},
{
"id":"3",
"name":"b",
"email":"test#gmail.com",
"expiryType":"premium"
},
]
can somebody please help me how to filter out objects where email is same but i want to keep the one with expiry Type is premium ? How to achieve this using Javascript
Expected output would be
const obj =
[
{
"id":"1",
"name":"a",
"email":"abc#gmail.com",
"expiryType":"premium"
},
{
"id":"3",
"name":"b",
"email":"test#gmail.com",
"expiryType":"premium"
},
]

Assuming you want to keep the latest year's entry, you can keep a Map of the email addresses and years you've seen. See comments:
// The new list
const filtered = [];
// Known emails
const known = new Map();
// Loop through...
for (const entry of obj) {
// Get this email and expiry
const {email, expiryYear} = entry;
// Get the previous info if any
const previous = known.get(email);
if (previous) {
// If the previous one is older than this one,
// replace it with this one
if (previous.expiryYear < expiryYear) {
filtered[previous.index] = entry;
}
} else {
// Add this to the known list and the filtered array
known.set(email, {
index: filtered.length,
expiryYear
});
filtered.push(entry);
}
}
const obj = [
{
"id":"1",
"name":"a",
"email":"abc#gmail.com",
"expiryYear":"2020"
},
{
"id":"2",
"name":"a",
"email":"abc#gmail.com",
"expiryYear":"2019"
},
{
"id":"3",
"name":"b",
"email":"test#gmail.com",
"expiryYear":"2020"
},
];
// The new list
const filtered = [];
// Known emails
const known = new Map();
// Loop through...
for (const entry of obj) {
// Get this email and expiry
const {email, expiryYear} = entry;
// Get the previous info if any
const previous = known.get(email);
if (previous) {
// If the previous one is older than this one,
// replace it with this one
if (previous.expiryYear < expiryYear) {
filtered[previous.index] = entry;
}
} else {
// Add this to the known list and the filtered array
known.set(email, {
index: filtered.length,
expiryYear
});
filtered.push(entry);
}
}
console.log(filtered);
This has the advantage of not constantly re-scanning the new list for known entries.

You can filter out whole object based on unique key you want as below.
const obj =
[
{
"id": "1",
"name": "a",
"email": "abc#gmail.com",
"expiryType": "premium"
},
{
"id": "2",
"name": "b",
"email": "abc#gmail.com",
"expiryType": "gold"
},
{
"id": "3",
"name": "b",
"email": "test#gmail.com",
"expiryType": "premium"
}
]
function arrayUnique(arr, uniqueKey) {
const flagList = []
return arr.filter(function(item) {
if (flagList.findIndex(flagItem => flagItem[uniqueKey] === item[uniqueKey]) === -1) {
flagList.push(item)
return true
}
})
}
Method Calling....
let newObj = arrayUnique(obj,'email')
Output:
newObj = [
{
"id": "1",
"name": "a",
"email": "abc#gmail.com",
"expiryType": "premium"
},
{
"id": "3",
"name": "b",
"email": "test#gmail.com",
"expiryType": "premium"
}
]
Hope this helps.

You can do it simply with 2 loops. Maybe not the fastes but the simplest:
function deleteDouble(array, objectKey) {
for (var i = 0; i < array.length; i++) {
for (var j = 0; j < array.length; j++) {
if (i == j) {
continue;
}
if (array[i][objectKey] == array[j][objectKey]) {
array.splice(i, 1);
i = 0;
j = 0;
break;
}
}
}
return array;
}
deleteDouble(obj, "email");

How apply ko.utils.arrayGetDistinctValues on two dimensional arrays

I have an ko.observableArray with two dimensions, i.e. "id" and "name".
Id will always be distinct, but name can hold the same value.
self.myArray = ko.observableArray( [
{ "id": "1", "name": "Barbara" }, 
{ "id": "2", "name": "Edwin" }, 
{ "id": "3", "name": "Barbara" } 
] );
However I want to filter the array so that my result holds only the first occurrence of "name".
The result I want is:
self. myFilteredArray = [
{ "id": "1", "name": "Barbara" }, 
{ "id": "2", "name": "Edwin" } 
];
I have been trying to figure this out using ko.utils.arrayGetDistinctValues(), but how can I utilize it on solely one chosen dimension?

You could use a computed for this:
viewModel.myFilteredArray = ko.computed(function() {
var rv = [], names = [];
for(var i=0; i<this.myArray().length; i++) {
if(names.indexOf(this.myArray()[i].name) === -1) {
rv.push(this.myArray()[i]);
names.push(this.myArray()[i].name);
}
}
return rv;
}, viewModel);

I can suggest a function, that loops through the array, builds map of property values for each item and checks, whether the current value was already added. Something like this:
function filterByFirstOccurance(arr, prop) {
var propValuesHash = {},
result = [];
for (var i = 0, l = arr.length; i < l; i++) {
var item = arr[i],
propValue = item[prop];
if (item.hasOwnProperty(prop) && !propValuesHash[propValue]) {
propValuesHash[propValue] = true;
result.push(item);
}
}
return result;
};
Fiddle

Get specific object by id from array of objects in AngularJS

I have a JSON file containing some data I d like to access on my AngularJS website. Now what I want is to get only one object from the array. So I d like for example Item with id 1.
The data looks like this:
{ "results": [
{
"id": 1,
"name": "Test"
},
{
"id": 2,
"name": "Beispiel"
},
{
"id": 3,
"name": "Sample"
}
] }
I'd like to load the data with AngularJS $http functionality like this:
$http.get("data/SampleData.json");
which is working. But how can I now get a specific data object (by id) from the array I get from $http.get ?

Using ES6 solution
For those still reading this answer, if you are using ES6 the find method was added in arrays. So assuming the same collection, the solution'd be:
const foo = { "results": [
{
"id": 12,
"name": "Test"
},
{
"id": 2,
"name": "Beispiel"
},
{
"id": 3,
"name": "Sample"
}
] };
foo.results.find(item => item.id === 2)
I'd totally go for this solution now, as is less tied to angular or any other framework. Pure Javascript.
Angular solution (old solution)
I aimed to solve this problem by doing the following:
$filter('filter')(foo.results, {id: 1})[0];
A use case example:
app.controller('FooCtrl', ['$filter', function($filter) {
var foo = { "results": [
{
"id": 12,
"name": "Test"
},
{
"id": 2,
"name": "Beispiel"
},
{
"id": 3,
"name": "Sample"
}
] };
// We filter the array by id, the result is an array
// so we select the element 0
single_object = $filter('filter')(foo.results, function (d) {return d.id === 2;})[0];
// If you want to see the result, just check the log
console.log(single_object);
}]);
Plunker: http://plnkr.co/edit/5E7FYqNNqDuqFBlyDqRh?p=preview

For anyone looking at this old post, this is the easiest way to do it currently. It only requires an AngularJS $filter. Its like Willemoes answer, but shorter and easier to understand.
{
"results": [
{
"id": 1,
"name": "Test"
},
{
"id": 2,
"name": "Beispiel"
},
{
"id": 3,
"name": "Sample"
}
]
}
var object_by_id = $filter('filter')(foo.results, {id: 2 })[0];
// Returns { id: 2, name: "Beispiel" }
WARNING
As #mpgn says, this doesn't work properly. This will catch more results. Example: when you search 3 this will catch 23 too

personally i use underscore for this kind of stuff... so
a = _.find(results,function(rw){ return rw.id == 2 });
then "a" would be the row that you wanted of your array where the id was equal to 2

I just want to add something to Willemoes answer.
The same code written directly inside the HTML will look like this:
{{(FooController.results | filter : {id: 1})[0].name }}
Assuming that "results" is a variable of your FooController and you want to display the "name" property of the filtered item.

You can use ng-repeat and pick data only if data matches what you are looking for using ng-show
for example:
<div ng-repeat="data in res.results" ng-show="data.id==1">
{{data.name}}
</div>

You can just loop over your array:
var doc = { /* your json */ };
function getById(arr, id) {
for (var d = 0, len = arr.length; d < len; d += 1) {
if (arr[d].id === id) {
return arr[d];
}
}
}
var doc_id_2 = getById(doc.results, 2);
If you don't want to write this messy loops, you can consider using underscore.js or Lo-Dash (example in the latter):
var doc_id_2 = _.filter(doc.results, {id: 2})[0]

If you want the list of items like city on the basis of state id then use
var state_Id = 5;
var items = ($filter('filter')(citylist, {stateId: state_Id }));

Unfortunately (unless I'm mistaken), I think you need to iterate over the results object.
for(var i = 0; i < results.length; i += 1){
var result = results[i];
if(result.id === id){
return result;
}
}
At least this way it will break out of the iteration as soon as it finds the correct matching id.

Why complicate the situation? this is simple write some function like this:
function findBySpecField(data, reqField, value, resField) {
var container = data;
for (var i = 0; i < container.length; i++) {
if (container[i][reqField] == value) {
return(container[i][resField]);
}
}
return '';
}
Use Case:
var data=[{
"id": 502100,
"name": "Bərdə filialı"
},
{
"id": 502122
"name": "10 saylı filialı"
},
{
"id": 503176
"name": "5 sayli filialı"
}]
console.log('Result is '+findBySpecField(data,'id','502100','name'));
output:
Result is Bərdə filialı

The only way to do this is to iterate over the array. Obviously if you are sure that the results are ordered by id you can do a binary search

$scope.olkes = [{'id':11, 'name':'---Zəhmət olmasa seçim edin---'},
{'id':15, 'name':'Türkyə'},
{'id':45, 'name':'Azərbaycan'},
{'id':60, 'name':'Rusya'},
{'id':64, 'name':'Gürcüstan'},
{'id':65, 'name':'Qazaxıstan'}];
<span>{{(olkes | filter: {id:45})[0].name}}</span>
output: Azərbaycan

If you can, design your JSON data structure by making use of the array indexes as IDs. You can even "normalize" your JSON arrays as long as you've no problem making use of the array indexes as "primary key" and "foreign key", something like RDBMS. As such, in future, you can even do something like this:
function getParentById(childID) {
var parentObject = parentArray[childArray[childID].parentID];
return parentObject;
}
This is the solution "By Design". For your case, simply:
var nameToFind = results[idToQuery - 1].name;
Of course, if your ID format is something like "XX-0001" of which its array index is 0, then you can either do some string manipulation to map the ID; or else nothing can be done about that except through the iteration approach.

I know I am too late to answer but it's always better to show up rather than not showing up at all :). ES6 way to get it:
$http.get("data/SampleData.json").then(response => {
let id = 'xyz';
let item = response.data.results.find(result => result.id === id);
console.log(item); //your desired item
});

The simple way to get (one) element from array by id:
The find() method returns the value of the first element in the array that satisfies the provided testing function. Otherwise undefined is returned.
function isBigEnough(element) {
return element >= 15;
}
var integers = [12, 5, 8, 130, 160, 44];
integers.find(isBigEnough); // 130 only one element - first
you don't need to use filter() and catch first element xx.filter()[0] like in comments above
The same for objects in array
var foo = {
"results" : [{
"id" : 1,
"name" : "Test"
}, {
"id" : 2,
"name" : "Beispiel"
}, {
"id" : 3,
"name" : "Sample"
}
]};
var secondElement = foo.results.find(function(item){
return item.id == 2;
});
var json = JSON.stringify(secondElement);
console.log(json);
Of course if you have multiple id then use filter() method to get all objects.
Cheers
function isBigEnough(element) {
return element >= 15;
}
var integers = [12, 5, 8, 130, 160, 44];
integers.find(isBigEnough); // 130 only one element - first
var foo = {
"results" : [{
"id" : 1,
"name" : "Test"
}, {
"id" : 2,
"name" : "Beispiel"
}, {
"id" : 3,
"name" : "Sample"
}
]};
var secondElement = foo.results.find(function(item){
return item.id == 2;
});
var json = JSON.stringify(secondElement);
console.log(json);

projectDetailsController.controller('ProjectDetailsCtrl', function ($scope, $routeParams, $http) {
$http.get('data/projects.json').success(function(data) {
$scope.projects = data;
console.log(data);
for(var i = 0; i < data.length; i++) {
$scope.project = data[i];
if($scope.project.name === $routeParams.projectName) {
console.log('project-details',$scope.project);
return $scope.project;
}
}
});
});
Not sure if it's really good, but this was helpful for me..
I needed to use $scope to make it work properly.

use $timeout and run a function to search in "results" array
app.controller("Search", function ($scope, $timeout) {
var foo = { "results": [
{
"id": 12,
"name": "Test"
},
{
"id": 2,
"name": "Beispiel"
},
{
"id": 3,
"name": "Sample"
}
] };
$timeout(function () {
for (var i = 0; i < foo.results.length; i++) {
if (foo.results[i].id=== 2) {
$scope.name = foo.results[i].name;
}
}
}, 10);
});

I would iterate over the results array using an angularjs filter like this:
var foundResultObject = getObjectFromResultsList(results, 1);
function getObjectFromResultsList(results, resultIdToRetrieve) {
return $filter('filter')(results, { id: resultIdToRetrieve }, true)[0];
}

Querying javascript objects using jQuery or other known js library

What is the best way to apply queries (such as regular expressions) on javascript objects to obtain a subset of some array or collection that follow some criteria, are there such plugin for jQuery, or some way to use jQuery or other known js library for this purpose?
for example:
var x=[{ firstName: "Tony",lastName="Mike" }, { firstName: "John", lastName="Jan"}];
var y = ????;//the first names of the objects in x where their last names follow the regular expression : bla-bla-bla

It appears as you are looking for JSONpath or the like.

using jQuery:
var x = [
{ firstName: "Sakher",lastName:"Sawan" },
{ firstName: "John", lastName:"Jan"}
],
y = $(x).map(function(a, obj){
return /^S/.test(obj.lastName) ? obj.firstName : null
});
Note that in some browsers you don't have to use jQuery to do this, as you can just as well use x.map in browsers that have Array.prototype.map (older browsers don't)

You should use some frameworks like dojo for doing these kind of operations.
look at the sample grid
http://dojotoolkit.org/reference-guide/dojox/grid/DataGrid.html
you can do all kind of operations on that.

It seems that you can do it by JS itself:
var re = ...; // regular espression
var y = [....]; // input array
var x = y.filter(function(el) { return re.test(el.firstName) } );
In x you will have filtered array where each element satisfy your conditions.

Check this link.
var jsonArray = [
{ "user": { "id": 100, "screen_name": "d_linq" }, "text": "to objects" },
{ "user": { "id": 130, "screen_name": "c_bill" }, "text": "g" },
{ "user": { "id": 155, "screen_name": "b_mskk" }, "text": "kabushiki kaisha" },
{ "user": { "id": 301, "screen_name": "a_xbox" }, "text": "halo reach" }
]
// ["b_mskk:kabushiki kaisha", "c_bill:g", "d_linq:to objects"]
var queryResult = Enumerable.From(jsonArray)
.Where(function (x) { return x.user.id < 200 })
.OrderBy(function (x) { return x.user.screen_name })
.Select(function (x) { return x.user.screen_name + ':' + x.text })
.ToArray();
// shortcut! string lambda selector
var queryResult2 = Enumerable.From(jsonArray)
.Where("$.user.id < 200")
.OrderBy("$.user.screen_name")
.Select("$.user.screen_name + ':' + $.text")
.ToArray();