A detailed description of JavaScript objects

Tag: Indicates select Alert No application developed his field obj

An overview of JavaScript objects

What is an object is, in fact, a type, that is, a reference type. The value of the object is an instance of the reference type.

A reference type in JavaScript is a data structure that organizes data and functionality together. It is also often called a class, but there is no such thing in JavaScript (impersonation).

Although JavaScript is an object-oriented language, it does not have the basic structure of classes and interfaces supported by traditional object-oriented languages.

It is an ideal choice for storing and transferring data in an application.

　　

How to create a JavaScript object-Create an object using the new operator

functionObjrun () {return' 123 ';}varbox =NewObject ();//An object was createdAlerttypeofbox);//object type is objects   //Create an attribute field for an objectBox.name = ' Li Tinghui '; Box.age= 28; Box.run=Objrun (); Alert ("My name is" +box.name+ ", I Am" +box.age+ "year old ...");//Get property fields for an objectalert (Box.run);//calling methods in an object

The new keyword can be omitted

var // The New keyword is omitted = ' Huang Jia ai '= A,alert ("My name is" +box.name+ ", I this year" +box.age+ "years old ...");     

How JavaScript objects are created-using literal notation

var box = {    // create attribute field    age:28,    function//  The method in the object        return ' run ';    }; Alert ("My name is" +box.name+ ", I Am" +box.age+ "year old ..."); Alert (Box.run ()); // calling methods in an object

Property fields can also be used as String forms

var box = {    // create attribute field    ' age ':};alert ("My name is" +box.name+ ", I'm this year" +box.age+ "years old .....");

Create objects by using literal methods, but you can use the traditional way when creating fields for objects

var box = {};     // literal method declares an empty object // traditional way to create field properties for an object box.age =;       // There are two ways to output a property // dot notation output alert ("My name is" +box[' name ']+ ", I am this year" +box[' age ']+ "years old ..."); // bracket notation Output, note the need to enclose the quotation marks

How JavaScript objects are created-display constructors to create objects

Whenever a function is used by the new operator, the function can become a constructor

var function () {  this. Name = "O2";  }  var New M (); alert (o2.name);

How to create a JavaScript object-object.create ()

var p = {    name:"O3"}; var o3 = object.create (p) alert (o3.name);

Passing an object as a parameter to a function

In the actual development process, we generally prefer the literal declaration method. Because it is clear, the syntax code is few, but also gives the person a kind of encapsulation feeling. Literals are also the preferred way to pass a large number of optional parameters to a function.

function // parameter is an object if　　(obj.name!=// determines if the attribute exists  if (obj.age! = undefined) alert (obj.age); }  var obj=' Li Tinghui ' , Box (obj);　　　　　　　　

　

Delete Object properties Using Delete

    var box == ' Orient card ';　　} alert (Box.name);　　 Delete  box.name; alert (box.name); // has been deleted, undefined

A detailed description of JavaScript objects