JS object definition

from ： Micro reading   https://www.weidianyuedu.com

Method 1 ： adopt var object={}   Object literal

(1), You can call the object direct quantity to customize an object . Object self face quantity is an expression , Each operation of this expression creates and initializes a new object .

var user = { x:1,y:2,z:3,pp:function(){  alert("22222222") }}

// Define an object literally , It is saved in the form of name value pairs

alert(user.y)   // Call the property

user.pp()   // Calling method

(2)   var student = {     // You can also wrap , Define each attribute name and value , Comma off , The last one without a comma , If you add it, it will be ignored , But in ie China will report an error , Better not add

"x":1,          // When defining the attribute name, you can use double quotation marks

'y':2,          // When defining attribute names, you can use single quotation marks

z:12.3,         // You can add any... When defining the attribute name

"for":" Use keywords to define attribute names. Use quotation marks ",  // If you use a keyword definition, you must use double quotation marks              man:{           // Objects can also be checked in

text:null,       // The attribute value of an object can be a variety of data types

text2:undefined,

married:true

},

dd:function(){alert("33333333")}

}

alert(student.x)

student.dd()

Method 2 ： adopt var obj = new Object(); Create objects

1、 Create a blank Object object

How to write it 1：var obj = new Object();

How to write it 2：var obj = {};

2、 Add properties and methods to the created object

var obj = {};

obj.name = ' Xiao Ming ';  // attribute

obj.showName = function(){  // Method

alert(this.name);

};

obj.showName();  // Method call

==========================================

1 <script>

2 var obj = new Object() // Created an object ,object Objects are also top-level objects in objects

3 var arry = new Array() // Created an array object

4 var date = new Date() // Create a time object

5 var reg = new RegExp("js") // Create a regular object 6

</script>

==========================================

===========================================

adopt object.create To create objects

1 <script>

2 var obj = Object.create({x:1})

3 var obj = Object.create(null) // Created an object without a prototype , There's no way

4 var obj = Object.create(obj.prototype) // Created an ordinary empty object

5 </script>

===========================================

Method 3 : Create objects through constructors

adopt instanceof Operator can detect whether an object is created by a specified constructor function

Be careful ：

It can be used through new Operator gets the object .

When you create an object with a constructor, you can receive parameters

The first letter of constructor function should be capitalized , Different from other general functions

function Person(name,age){   // Create a person Function of

this.name =name;      m.weidianyuedu.com    // Here this Corresponding to the object obj

this.age = age

}

var obj = new Person("ziksang",21)  // Using a constructor to create an object

alert(obj.name)        //=>ziksang  Use the object name . Object to get the attribute value

alert(typeof obj)      //=> use typeof To detect obj Is it an object type , return object

alert(obj instanceof Person)  //=> use instanceof To detect objcet Is it right? person The object constructed by function , return true

+++++++++++++++++++++++++++++++++++++++++++++++++++++++

Method （1）== Method （2）

(1)

var obj = new Object();

obj.name = " The Monkey King ";

obj.age = 18;

obj.sayName = function(){    alert(obj.name);         };

function fun(){    alert(obj.name);  };

obj.sayName();

fun();

(2)

var obj2 = {

name:" Pig eight quit ",

age:18,

sayName:function(){  alert(obj2.name);     }

};

obj2.sayName();