Home > Developer > JavaScript
Example 1: Defining a person's information through native JS and object-oriented JS
<!DOCTYPE HTML><HTML><Head><MetaCharSet= ' utf-8′><title></title></Head><Body><Script>//define a person's information by JS codevarname=' Lisi'var age = ' 30′;var marry = False;alert (name+ '-' +age+ '-' +marry ');//define a person's information function () by object-oriented () {}// Instantiate the person class var p1 = new Person ();//Assign a value for object P1 Name\age\marry Property P1.name = ' Zhangfei';p 1.age=' -;p 1.marry= false; alert (P1.name+'-'+P1.age+'-'+marry);</Script></Body></HTML>
2. Creation of custom Classes
In JavaScript code, there is no class keyword to define classes, only function, when we define a function through the functions keyword, such as the person function, then the system will consider the function is the same name Class (person Class) constructor, So this is the basic syntax for defining classes in JavaScript code.
Class Person {
function person () {}//constructor for the person class with the same name
}
3. Custom class Execution Process1) Open up memory space
2) Execute constructor (constructor)
Example code:
<!DOCTYPE HTML><HTML><Head><MetaCharSet= ' utf-8′><title></title></Head><Body><Script>//defining a custom classfunctionPerson () {alert (' Hello ');}varP1= NewPerson ();</Script></Body></HTML>
The above code verifies that when we execute the 14th line of code, the system automatically pops up Hello, so we can prove that the person function is the constructor (constructor) under the person class with the same name
4, about the use of attributesQuestion: Why do we use classes to create an object?
A: We create objects to hold more data, and in JavaScript code we can save the data through attributes.
Defines the basic syntax for a property:
Object. Property = property Value
Basic syntax for using attributes:
Object. Properties
Or
Object [' Properties ']
Example code:
<!DOCTYPE HTML><HTML><Head><MetaCharSet= ' utf-8′><title></title></Head><Body><Script>//1. Defining ClassesfunctionPerson () {}//2. Instantiate the person class and create an objectvarP1= NewPerson ();//3. Binding name.email.address Three properties for P1P1.name=' Lisi';p 1.email = ' [email protected]';p 1[' address ']=' Guangzhou, Guangdong province';//4. name.email.address attributes such as alert (p1.name); alert (p1.email); alert (p1.address);</script></body>
Question: Do we know that there is no class keyword in JavaScript, only function, when we define a function by function, is it referenced in a functional way, or is it referenced in an object-oriented way?
A: In JavaScript, the function is called in object-oriented form, because all properties and methods defined in the global scope are added to the Window object as attributes.
In JavaScript, everything is an object.
var str= ' Hello '; String
var num=10; Number
var marry=true; Boolean
5. Attribute typeThe object name. Properties
Object name [' property ']
6. Three major keywordstypeof (operator, which is not a function): Determines the data type of the current variable
Instanceof: Determines whether the current object is an instance of a class
Constructor: Returns the constructor or constructor of the current object (returns the constructor pointed to by the prototype object)
How to use:
Alert (typeof p);
Alert (P instanceof person);
alert (p.constructor);
Example code:
<!DOCTYPE HTML><HTML><Head><MetaCharSet= ' utf-8′><title></title></Head><Body><Script>//1. Define a custom classfunctionPerson () {//constructors for the person class with the same name}//Create an ObjectvarP1= NewPerson ();//determine the data type of a P1 objectAlert (typeofp1);//determine if the P1 object is an instance of the person classAlert (P1instanceofPerson );//returns the constructor for the P1 objectalert (p1.constructor);</Script></Body></HTML>
Kill lui lei Dog---javascript no:21 custom Class 1
Start building with 50+ products and up to 12 months usage for Elastic Compute Service
1 on 1 presale consultation
24/7 Technical Support 6 Free Tickets per Quarter Faster Response
Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.
A comprehensive suite of global cloud computing services to power your business
Payment Methods We Support
