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:
Code #1:

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); 

Output:

1 is True.
0 is False.
myVar = false

Code #2:

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()); 
 
 
 
 
         

Output:

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

See also:

JavaScript | Boolean.prototype with Examples

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