{} it's an object in the JavaScript. An object contains a set of properties and functions. Example var book = {Name: "Wizard of the Mediterranean", Price: 120};

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{} it's an object in the JavaScript. An object contains a set of properties and functions. Example var book = {Name: "Wizard of the Mediterranean", Price: 120}; | standard ES5

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{} it's an object in the JavaScript | standard ES5

last updated: 1 Augusta 2020

Object in the JavaScript it is a set of properties
Example: The workbook has properties
• name
• author's name
• price
• Pages

Create a populated object

To create an object you need to write
var object name =
{
property 1 : value 1,
"property 2" : value 2, // you can write the property in quotation marks
...
};

Html Example

<html>
<body>

<script>
     // create an object
     var book1 =
     {
          // property set
          Name: "Wizard of the Mediterranean",
          Price: 120
     };

     // on the screen we will see "Wizard of the Mediterranean"
     alert(book1.Name);

     // create an object
     var book2 =
     {
          // property set
          "Name": "Lord of the Rings",
          "Price": 60
     };

     // on the screen we will see "Lord of the Rings"
     alert(book2.Name);
</script>

</body>
</html>

Create an empty object

An empty object can be created in 3 ways:

Method 1

var book1 = {};

Method 2

var book1 = new Object();

Method 3

var book1 = Object.create( Object.prototype );

To add a property to an object

Method 1

book1.Name = "Wizard of the Mediterranean";

Method 2

book1["Name"] = "Wizard of the Mediterranean";

Html Example

<html>
<body>

<script>
     // Method 1. Create an empty object
     var book1 = {};

     // Add a property
     book1.Name = "Wizard of the Mediterranean"; // method 1
     book1["Author"] = "Ursula Le Guin"; // method 2

     // on the screen we will see "Wizard of the Mediterranean Ursula Le Guin"
     alert(book1.Name + " " + book1.Author);

     // Option 2. Create an empty object
     var book2 = new Object();

     // add a property
     book2.Name = "Lord of the Rings"; // method 1
     book2["Author"] = "Nick Perumov"; // method 2

     // on the screen we will see "The Lord of the Rings Nick Perumov"
     alert(book2.Name + " " + book2.Author);
</script>

</body>
</html>

Take, get a property from an object

Method 1

var value1 = book1.Name;

Method 2

var value1 = book1["Name"];

Html Example

<html>
<body>

<script>
     // create an object
     var book =
     {
          // property set
          Name: "Wizard of the Mediterranean",
          Author : "Ursula Le Guin",
     };

     // get the property of the object (method 1)
     var value1 = book.Name;
     // value1 = "Wizard of the Mediterranean";

     // get the property of the object (option 2)
     var value2 = book['Name'];
     // value2 = "Wizard of the Mediterranean";

</script>

</body>
</html>

Select (enumerate) all elements in the object

Html Example

<html>
<body>

<script>
     // create an object
     var book =
     {
          // property set
          Name: "Wizard of the Mediterranean",
          Author : "Ursula Le Guin",
     };

     // on the screen we will see
     for( key in book )
     {
          // iteration 1
          // key = "Name"
          // book[key] = "Wizard of the Mediterranean"

          // iteration 2
          // key = "Author"
          // book[key] = "Ursula Le Guin"
     }
</script>

</body>
</html>

Create a complex object

Html Example

Delete an object

delete book.Name;

Comparison on empty

if (book.Name == undefined)
alert("empty");
if (book.Name != undefined)
alert("not empty");

Html Example

<html>
<body>

<script>
     // create an object
     var book =
     {
          // property set
          Name: "Wizard of the Mediterranean",
          Author : "Ursula Le Guin",
     };

     // on the screen we will see 'not empty'
     if (book.Name != undefined)
          alert("not empty");

     // delete the object
     delete book.Name;

     // on the screen we will see 'empty'
     if (book.Name == undefined)
          alert("empty");
</script>

</body>
</html>

An object can contain functions

Html Example

<html>
<body>

<script>
     // create an object
     var book =
     {
          // property set
          Name: "Wizard of the Mediterranean",
          Author : "Ursula Le Guin",

          // nested set of properties
          OtherInfo :
          {
               Price: 120,
               PagesCount: 90
          },

          // function
          myShow : function(title)
          {
               alert(title + ' ' + this.Name + ' ' + this.OtherInfo.Price);
          }
     };

     // calling a function on an object
     book.myShow('Hello');
     // on the screen we will see 'Hello Wizard of the Mediterranean 120'
</script>

</body>
</html>

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{...} = объект в JavaScript заполняем из переменных класса или другим объектом. Пример: const {name, total, price} = b.myProps; | standard ES5