Object-oriented JavaScript-002

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1<script type= "Text/javascript" >2     3     //Define the person constructor4     varperson =function(firstName) {5        This. FirstName =FirstName;6     };7 8     //Making sure that this points to the right thing regardless of what the object is instantiated can be difficult. However, there is a simple idiom to make this easier.9     varperson =function(firstName) {Ten       if( This instanceofPerson ) { One          This. FirstName =FirstName; A}Else { -         return NewPerson (firstName); -       } the     } -  -     //Add A couple of methods to Person.prototype -Person.prototype.walk =function(){ +Console.log ("I am walking!"); -     }; +  APerson.prototype.sayHello =function(){ atConsole.log ("Hello, I ' m" + This. firstName); -     }; -  -     //Define the Student constructor -     functionStudent (FirstName, subject) { -       //Call the parent constructor, making sure (using Function#call) in       //That ' This ' is set correctly during the call -Person.call ( This, firstName); to  +       //Initialize our student-specific properties -        This. Subject =subject; the     } *  $     //Create A Student.prototype object that inherits from Person.prototype.Panax Notoginseng     //note:a Common error Here's to use ' new person ' to create the -     //Student.prototype. That's incorrect for several reasons, not least the     //That we don ' t has anything to give person for the "FirstName" +     //argument. The correct place-to-call person are above, where we call A     //it from Student. theStudent.prototype = Object.create (Person.prototype);//See Note below +  -     //Set the "constructor" property to refer to Student $Student.prototype.constructor =Student; $  -     //Replace The "SayHello" method -Student.prototype.sayHello =function(){ theConsole.log ("Hello, I ' m" + This. FirstName + ". I ' m studying " -+ This. Subject + ".");Wuyi     }; the  -     //Add A "Saygoodbye" method WuStudent.prototype.sayGoodBye =function(){ -Console.log ("goodbye!"); About     }; $  -     //Example Usage: -     varStudent1 =NewStudent ("Janet", "Applied Physics"); -Student1.sayhello ();//"Hello, I ' m Janet." I ' m studying applied Physics. " AStudent1.walk ();//"I am walking!" +Student1.saygoodbye ();//"goodbye!" the  -     //Check that instanceof works correctly $Console.log (student1instanceofperson);//true theConsole.log (student1instanceofStudent);//true the  the     //if on older JavaScript engines without object.create, one can either use a "Polyfill" (aka "shim", see the linked art icle), or one can use a function that achieves the same result, such as: the     functionCreateObject (Proto) { -         functionctor () {} inCtor.prototype =Proto; the         return Newctor (); the     } About  the     //Usage: theStudent.prototype = CreateObject (Person.prototype);

Object-oriented JavaScript-002