JavaScript | Boolean.prototype with Examples

The Boolean.prototype is an inbuilt property in JavaScript which is used to add a new property to the all Boolean instances. There is constructor prototype which is used to add properties or methods to all Boolean objects.
Syntax:

Boolean.prototype.name = value

Here “name” specifies the property or method name to be used and “value” specifies the value used by the function.
Some methods related to Boolean.prototype property :

  • Boolean.prototype.valueOf(): It simply returns the value of boolean object.
  • Boolean.prototype.toString(): This method returns a string according to the Boolean value.

JavaScript code to show the working of this property:
Example 1:



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<script>
        function check(v1) {
            if (v1 == true)
                return (v1 + " is True.");
            else
                return (v1 + " is False.");
        }
  
        //adding a new property
        Boolean.prototype.myVar = false;
  
        //adding a new method
        Boolean.prototype.myMethod = check;
  
        //creating a new boolean object
        var Obj1 = new Boolean();
  
        document.write(Obj1.myMethod(1) + "<br>");
        document.write(Obj1.myMethod(0) + "<br>");
        document.write("myVar = " + Obj1.myVar);
      
</script>

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Output:

1 is True.
0 is False.
myVar = false

Example 2:

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<script>
        Boolean.prototype.CheckGeek = function(pro) {
            if (pro == true) {
                return "Pro Geek";
            } else {
                return "Geek";
            }
        };
  
        //creating a new boolean object
        var Obj = new Boolean(true);
  
        document.write("Obj.CheckGeek(true) = " 
                          + Obj.CheckGeek(true) + "<br>");
        document.write("Obj.CheckGeek(false) = " 
                         + Obj.CheckGeek(false) + "<br>");
        document.write("Obj.valueOf() = " 
                                + Obj.valueOf() + "<br>");
        document.write("Obj.toString() = " 
                                        + Obj.toString());
      
</script>            

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Output:

Obj.CheckGeek(true) = Pro Geek
Obj.CheckGeek(false) = Geek
Obj.valueOf() = true
Obj.toString() = true

See also:



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