JavaScript Encapsulation

JavaScript Encapsulation

The JavaScript Encapsulation is basically a process of binding the data with the functions acting on the same data and allows to control and validate the data. There are two methods to achieve an encapsulation in the JavaScript: -

• By using setter methods to set the data and getter methods to receive that data.
• By using var keyword to make data members private.

Using these following properties, encapsulation in JavaScript allows us to handle an object:

• Write only :Only the setter methods is used in this case.
• Read/Write :In this property, getter method is used to read the data and the setter method is used to set the data.
• Read only :Only the getter methods used in this case.

Examples of JavaScript Encapsulation

1. Here is an 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("Sonu");  
     stud.setMarks(95);  
     document.writeln(stud.getName()+" "+stud.getMarks());  
</script> 

2. JavaScript Encapsulation example in the context of validation

Here is an example to validate the marks of a student:

<script>
class Student  
  {  
    constructor()  
    {  
       var name;  
       var marks;  
    }  
        getName()  
        {  
          return this.name;  
        }  
      setName(name)  
      {  
        this.name=name;  
      }  
        
      getMarks()  
      {  
        return this.marks;  
      }  
    setMarks(marks)  
    {  
        if(marks<0||marks>100)  
        {  
          alert("Invalid Marks");  
        }  
      else  
        {  
          this.marks=marks;  
        }  
    }  
    }  
    var stud=new Student();  
     stud.setName("Sonu");  
     stud.setMarks(110);//alert() invokes  
     document.writeln(stud.getName()+" "+stud.getMarks());  
</script> 

3. JavaScript Encapsulation example in the context of Prototype-based approach.

Here is an example where prototype based encapsulation is performed:

<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("Anand",95);  
  document.writeln(stud.name+" "+stud.marks);  
</script>