JavaScript does not protect the property name hasOwnProperty

JavaScript's property name hasOwnProperty is not protected

As a web developer, I have faced various challenges in my journey of developing web applications. One of the challenges I faced was related to the security of JavaScript's property name hasOwnProperty.

The Issue

JavaScript allows developers to check if an object has a property using the hasOwnProperty method. This method returns a boolean value indicating whether an object has a property with the given name.

const obj = { name: 'Raju' };

console.log(obj.hasOwnProperty('name')); // true
console.log(obj.hasOwnProperty('age')); // false

However, the problem arises when an object has a property with the name 'hasOwnProperty'.

const obj = { hasOwnProperty: 'Raju' };

console.log(obj.hasOwnProperty('hasOwnProperty')); // TypeError: Property 'hasOwnProperty' of object #<Object> is not a function

In the above code, when we try to use the hasOwnProperty method on an object that has a property with the name 'hasOwnProperty', it throws an error. This is because the method is overwritten by the property and is no longer available as a method.

The Solution

One way to avoid this issue is to use the Object.prototype.hasOwnProperty method instead of the object's own hasOwnProperty method.

const obj = { hasOwnProperty: 'Raju' };

console.log(Object.prototype.hasOwnProperty.call(obj, 'hasOwnProperty')); // true

In the above code, we are using the call method to invoke the hasOwnProperty method from the Object prototype.

Another way to avoid this issue is to use the ES6 Reflect API's Reflect.has method, which allows us to check if an object has a property regardless of its own hasOwnProperty method.

const obj = { hasOwnProperty: 'Raju' };

console.log(Reflect.has(obj, 'hasOwnProperty')); // true

Conclusion

JavaScript's property name hasOwnProperty is not protected, and it can cause issues when trying to access an object's properties using the hasOwnProperty method. However, we can avoid this issue by using the Object.prototype.hasOwnProperty method or the Reflect API's Reflect.has method.