Initial exposure to object-oriented Javascript

I. object scope

Function classa () {var v = "I Am a variable v"; this. V = "I'm property v"; var me = This; classa. prototype. F = function () {alert ("I Am a function for external access");} function _ F () {alert ("I am just an internal function, external access to me is not allowed. ");} Classa. prototype. f2 = function () {alert (V); // OK alert (this. v); // OK _ F (); // OK f (); // This. F (); // OK} function _ F2 () {f (); // This. F (); // error me. F (); // OK} var obja = new classa (); alert (obja. v); // display "I Am a property v" obja. f2 (); obja. _ F2 (); // The system reports an error, indicating that the object is missing

Ii. Rewrite

Function classa () {var v = "I Am a variable v"; this. V = "I'm property v"; if (typeof classa. _ initialized = "undefined") {classa. prototype. F = function () {alert ("I Am a function for external access");} classa. _ initialized = true;} function _ F () {alert ("I am just an internal function and cannot access me externally. ") ;}} Var obja = new classa (); obja. V = "I am the property V, and now the bird is assigned a new value"; classa. prototype. F = function () {alert ("I Am a function that is accessible to external users and is now rewritten");} alert (obja. v); // display "I Am a property V, now being assigned a value again" obja. F (); // display "I Am a function that is accessible to external users and is now rewritten"

Function classa () {This. V = "I'm property v"; if (typeof classa. _ initialized = "undefined") {classa. prototype. F = function () {alert ("I Am a static function for external access F");} classa. _ initialized = true;} This. f2 = function () {alert ("I Am a function for external access F2") ;}} var obja1 = new classa (); var obja2 = new classa (); classa. prototype. F = function () {alert ("I Am a static function f that is accessible to external users. It is modified. ");} Obja1.f2 = function () {alert (" I Am a function F2 for external access, bird modified by obja1 ");} obja1.f (); // I am a static function f that is accessible to external users. Obja2.f (); // I am a static function f that can be accessed externally. Obja1.f2 (); // I am the function F2 that can be accessed externally, and obja1 modifies bird obja2.f2 (); // I am the function F2 that can be accessed externally.

Iii. Inheritance

Function classa () {This. va = "I am the attribute VA of classa"; if (typeof classa. _ initialized = "undefined") {classa. prototype. F = function () {alert ("I Am a static function f that classa can provide external access");} classa. _ initialized = true;} This. f2 = function () {alert ("I Am a function for external access F2") ;}} function classb () {This. VB = "I am the classb attribute VB";} classb. prototype = new classa (); var obja = new classa (); var objb = new classb (); alert (objb. va); // I am classa Attributes of vaalert (objb. VB); // The attribute vbobjb of classb. F (); // I am a static function fobjb that classa can provide external access. f2 (); // I am a function that can be accessed externally. f2classb. prototype. F = function () {alert ("I Am a static function f that classa can provide external access, and it is modified by classb. ");} Obja. F (); // I am a static function fobjb that classa can provide external access. F (); // I am a static function f provided by classa for external access, and it is modified by classb.

References:

Http://www.w3school.com.cn/js/pro_js_object_defining.asp