Javascript объект добавить элемент

JavaScript append new elements to an object

The way to append (or add) new elements to your JavaScript object depends on whether you are adding a new element to a parent Node object of a DOM tree or to a regular JavaScript object. This tutorial will show you how to append to both objects.

First, let’s see how you can append elements to a parent Node object

Append elements to a Node object

The Node object is a representation of HTML elements that you can select using the selector methods of the document object. For example, suppose you have the following code on your HTML page:

You can select the tag using the following selector methods:

  After selecting the object, you can append new elements to it using the append() method. You can append any valid Document element (HTML tags) or even just a text as follows:

   You’ll see the tag “Hello World” appended to the just like the code below:

 The append() method always adds new element next to the last child of the parent element, so appending two elements will cause the second one appended after the first:

The code above will generate the following HTML structure:

 The append() method can accept many document elements as its argument.

And that’s how you append new elements to a Node object. Let’s see how you can append elements to a regular JavaScript object next.

Append to JavaScript object

When you need to append new elements to your JavaScript object variable, you can use either the Object.assign() method or the spread operator. Let me show you an example of using both.

First, the Object.assign() method will copy all properties that you defined in an object to another object (also known as source and target objects).

To use Object.assign() , you need to pass one target object and one or more source objects:

Knowing this, you can easily append new elements or properties to an object as follows:

Alternatively, you can also use the spread operator to combine two or more objects as follows:

And that’s how you can append new elements to objects using JavaScript.

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How to add an element to a javascript object?

In JavaScript, the object is a real-time entity that contains properties and methods. In simple words, we can say that object is an instance of a class. It stores the data in the form of key and value pairs. The keys are usually referred to as properties and the values are referred to as property values.

There are two ways to define an object in JavaScript.

Syntax

Using dot(.) operator

In JavaScript, using the dot(.) operator we can access a variable which is stored in an object. The dot(.) operator will act as a connector between the object and the variable to be added.

Not only does this operator help in adding new elements to the object but also will be used in accessing the existing elements in an object anywhere else in the program.

let obj = ; obj.property = value;

Let’s discuss this method with a proper example.

Example

In the example program below, we have used the dot(.) operator method to access and add the elements in an object.

!DOCTYPE html> html lang="en"> head> title>Add Element in an Object/title> /head> body> script> var student =  name: 'abc', age: 20, city: 'Hyderabad', > student.marks = 80; document.write( "Name: " + student.name + "
" + "Age: " + student.age + "
" + "City: " + student.city + "
" + "Marks: " + student.marks ) console.log(student); /script> /body> /html>

Using the assign () method

In JavaScript, assign() is an in-built method. Using the assign() method, we can assign or add a new value to an existing object or we can create the new object without changing the existing object values.

Syntax

In JavaScript assign (target, source) method takes two parameters, first one is a target which usually means that we can target the existing object or we can put an empty object on the target’s place, so it will create a new object without changing the existing object.

And source means the property we want to assign an object to.

Example 1

Let’s understand how the assign () method adds a new element to an object in JavaScript without changing the existing object.

In the example, we have used the assign () method to add a new element to an existing object. For that, we used an empty target place and are creating a new object so it does not change the existing object values.

!DOCTYPE html> html lang="en"> head> title>Add Element in an Object/title> /head> body> script> var book =  name: 'English', price: 250, > var newobj = Object.assign(>, book, publishyear : 2015>); document.write( "Name: " + newobj.name + "
" + "Price: " + newobj.price + " 
" + "Publish year: " + newobj.publishyear ) /script> /body> /html>

Example 2

In this example, we will look at how assign() method works by modifying the existing object.

In the program, we are giving the target parameter in the assign method as an existing object name so that it will change the existing object value as well. Let us look at how that happens in the example below −

!DOCTYPE html> html lang="en"> head> title>Add Element in an Object/title> /head> body> script> var book =  name: 'English', price: 250, > var newobj = Object.assign(book,publishyear : 2015>); document.write( "Name: " + newobj.name + "
" + "Price: " + newobj.price + " 
" + "Publish year: " + newobj.publishyear ) /script> /body> /html>

Using square [] bracket

Using square [] bracket: In JavaScript, we can use [] brackets to add elements to an object. This is another way to add an element to the JavaScript object.

let obj = <>; obj[property] = value;

Example

In the example program below, we have used square [] brackets to fetch the array of elements in any particular index. Also we can add the element to an array.

!DOCTYPE html> html lang="en"> head> title>Add Element in an Object/title> /head> body> script> var student =  name: 'abc', age: 20, > student['city'] = 'Hyderabad'; document.write( "Name: " + student.name + "
" + "Age: " + student.age + "
" + "City: " + student.city ) console.log(student); /script> /body> html>

Источник

How to Add an Element to object JavaScript

In this tutorial, we will see how to add an element to a JavaScript object.

JavaScript object is a container that contained properties and methods. We can add properties to an empty object or an existing object.

Add an Element to an existing object

Let’s take an example first. Suppose we have an object user that has some properties i.e. id, name, and age like below.

Now if you want to add new property i.e. address. So how to do that?

; user.address = "NY"; console.log(user.address);

You can also add elements to an object by adding the key and value like this user[‘address’] = «NY»;

Add Element to an empty object

You can create an object by object literal i.e. curly braces <> or by using new keyword i.e. const user = new Object(); After that add new elements or property to it.

; user.id = 5; user.name = "John"; user.age = 35; user.address = "NY"; console.log(user.id + " " + user.name + " " + user.address);

Append element to object using Object.assign()

The Object.assign() method will copy all properties from source to target object. Let’s take an example first.

; const newUser = Object.assign(user, ); console.log(newUser);

Append element to object using spread operator

By using the spread operator, you can also combine two or more objects into a new object.

; const user_address = < mob: 12345678, email: "john@doe.com" >let newUser = >; console.log(newUser);

JavaScript object is mutable. That means after creating an object you can change its state. Let’s check an example.

; const newUser = user; newUser.address = "NY" newUser.id = 2; console.log(newUser); console.log(user);

You can see in the above example where the output is the same. That means the user and newUser are the same objects. The object newUser is not a copy of the user.

Conclusion

I think the above methods will help you to add an element to a JavaScript object. That’s all for today’s tutorial. You can also learn something new in JavaScript from our JavaScript Tutorial. If you have any questions please comments below.

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JavaScript: Как добавить новый элемент в объект?

В этой записи я хочу рассказать как добавить или удалить элемент из объекта в JavaScript. Это очень просто, но многие новички, как и я раньше, часто путались в этом.

Создадим объект для примера

У нас есть простой объект, внутри которого есть такие данные как name (имя), last_name (фамилия) и website (сайт). Данные могут быть абсолютно любыми, но в целях этой записи они будут именно такими.

Добавление нового элемента

obj.country = 'ru'; // добавит новый ключ "country" в объект cо значением "ru" obj['city'] = 'Moscow'; // так же добавит новый ключ, только "city" со значением "Moscow"

В коде выше все понятно, но лишь придам ясности: вы можете добавлять новые значения в объект в синтаксисе объекта, используя «.» и ключ или же обычный формат массива. Если вы объявите как массив, то obj все равно остается объектом, так как ранее вы его обозначили именно таким благодаря <> .

Создать объект внутри объекта

obj.other_obj = <>; // создадим новое значение other_obj в obj и сделаем его объектом

Теперь добавим туда какие-нибудь данные:

obj.other_obj.first = 'первый ключ нового объекта'; obj.other_obj.second = 'второй';

Мы создали два новых значения first и second внутри other_obj .

Удаление элемента

delete obj.name; // возвращает: true

Вы можете воспользоваться delete , которая может удалять элементы из объектов. Весь объект таким образом удалить нельзя, но если вам это нужно, то вы можете сделать так:

obj = <>; // Сделает объект снова пустым

На этой все, если у вас остались какие-то вопросы по объектам в JavaScript, пишите ниже комментарий, постараюсь вам помочь.

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