If you are considering adding an isEqual() method to all instances of the global Object type, you can achieve this in JavaScript by extending the prototype of Object. This will enable all object instances to automatically inherit the new method.
However, it is important to note that modifying native prototypes like this is generally discouraged due to potential conflicts with existing code. Changing the behavior of Object.prototype could lead to unforeseen issues and errors in other parts of your program.
The naive approach of directly adding a method to Object.prototype can result in unexpected consequences, such as making the property enumerable for all objects, which may not be desired.
In summary, the recommended advice is to avoid altering native prototypes in this manner.
If you still wish to proceed with adding the isEqual() method despite the risks, TypeScript provides support for declaration merging to extend existing interfaces:
interface Object {
isEqual(object: object): boolean;
}
By implementing this interface, the compiler will expect all instances of Object to have an isEqual() method. Additionally, consider using a declare global { } block for module-based implementations (global augmentation).
To actually implement the method, you can use Object.defineProperty() to ensure that the method name is non-enumerable:
Object.defineProperty(Object.prototype, 'isEqual', {
value(object: object) {
return JSON.stringify(this) === JSON.stringify(object);
},
configurable: true,
enumerable: false
});
This approach allows you to add the method without affecting enumeration loops over objects.
You can test the functionality by comparing two objects for equality:
interface Foo { a: number, b: string };
const o1: Foo = { a: 1, b: "two" };
const o2: Foo = { b: "two", a: 1 };
console.log(o1.isEqual(o2)); // false
The comparison should output false, indicating that the isEqual() method is functioning correctly. Remember to handle object properties appropriately when performing comparisons.
Link to Playground for Testing Code