JavaScript Learning Notes (vii)----object-oriented programming

1. Properties of an Object

There are two types of properties in ECMAScript: Data properties and accessor properties.

1) Data properties: There are 4 properties that describe their behavior.

• [[writable]]: Indicates whether the value of the property can be modified, by default, True.

 var  person = {};alert ( typeof  person); // object    Object.defineproperty (person, "name" ,{  Writable:     false   Span style= "color: #000000;" >    value: " Yoyo "}); alert (person.name);  // yoyo  person.name = "Anne" ;alert (Person.name);  // yoyo  

 var  person = {};alert ( typeof  person); // object  Object.defineproperty (person, "name" ,{  Writable:      true     ,   value :  "Yoyo"  // yoyo  person.name = "Anne" ;alert (Person.name);  // anne  

• [[Configurable]]: Indicates whether the property can be modified from a new definition by deleting the attribute from the delete, or whether it can modify the attributes of the property or modify the property to an accessor property. The default value is true.

var person = {};object.defineproperty (person,"name", {    configurable:false ,    value:"Yoyo"//YoyoDelete//  Yoyo

var person = {};object.defineproperty (person,"name", {    configurable:true ,    value:"Yoyo"//YoyoDelete//  Undefined

• [[[Enumerable]]: Can return a property by for-in loop, default is True
• [[Value]]: Contains the data value for this property. When reading a property value, read from this position, and when writing the value of the property, save the new value in this position. The default value is undefined.

JavaScript Learning Notes (vii)----object-oriented programming