JavaScript Encapsulation

The JavaScript Encapsulation is a process of binding the data (i.e. variables) with the functions acting on that data. It allows us to control the data and validate it. To achieve an encapsulation in JavaScript: –

• Use var keyword to make data members private.
• Use setter methods to set the data and getter methods to get that data.

The encapsulation allows us to handle an object using the following properties:

Read/Write – Here, we use setter methods to write the data and getter methods read that data.

Read Only – In this case, we use getter methods only.

Write Only – In this case, we use setter methods only.

JavaScript Encapsulation Example

Let’s see a simple example of encapsulation that contains two data members with its setter and getter methods.

<script>  

class Student  

  {  

    constructor()  

    {  

       var name;  

       var marks;  

    }  

        getName()  

        {  

          return this.name;  

        }  

      setName(name)  

      {  

        this.name=name;  

      }  

        

      getMarks()  

      {  

        return this.marks;  

      }  

    setMarks(marks)  

    {  

      this.marks=marks;  

    }  

  

    }  

    var stud=new Student();  

     stud.setName("John");  

     stud.setMarks(80);  

     document.writeln(stud.getName()+" "+stud.getMarks());  

</script>

Output:

John 80

JavaScript Encapsulation Example: Validate

In this example, we validate the marks of the student.

<script>  

class Student  

  {  

    constructor()  

    {  

       var name;  

       var marks;  

    }  

        getName()  

        {  

          return this.name;  

        }  

      setName(name)  

      {  

        this.name=name;  

      }  

        

      getMarks()  

      {  

        return this.marks;  

      }  

    setMarks(marks)  

    {  

      this.marks=marks;  

    }  

  

    }  

    var stud=new Student();  

     stud.setName("John");  

     stud.setMarks(80);  

     document.writeln(stud.getName()+" "+stud.getMarks());  

</script>

Output:

John undefined

JavaScript Encapsulation Example: Prototype-based approach

Here, we perform prototype-based encapsulation.

<script>  

function Student(name,marks)  

{  

  var s_name=name;  

  var s_marks=marks;  

  Object.defineProperty(this,"name",{  

    get:function()  

    {  

      return s_name;  

    },  

  set:function(s_name)  

  {  

    this.s_name=s_name;  

  }  

    

});  

   

    Object.defineProperty(this,"marks",{  

    get:function()  

    {  

      return s_marks;  

    },  

  set:function(s_marks)  

  {  

    this.s_marks=s_marks;  

  }  

    

});  

    

}  

  var stud=new Student("John",80);  

  document.writeln(stud.name+" "+stud.marks);  

</script

Output:

John 80