Why Is Manually Setting the `constructor` Property in Javascript Non-Idiomatic?

The Significance of Javascript's Constructor Property Explained

In Javascript, understanding the constructor property is crucial when navigating the complexities of object-oriented programming. Unlike classical inheritance models, Javascript relies on the constructor and prototype properties.

The constructor property primarily serves as an informational mechanism, indicating the function used to create an object using the new operator. For example, new Bar() assigns the value Bar to the constructor property, revealing which constructor was invoked.

On the other hand, the prototype property plays a key role in resolving property lookups. When an object lacks a specific attribute, Javascript searches within its own properties and then recursively ascends through the prototype chain, including the proto property, until the requested attribute is found.

In the example you provided, the object b inherits from Foo's prototype, as expected. However, you may wonder about the significance of manually setting Bar.prototype.constructor = Bar.

This practice is not strictly necessary and is considered non-idiomatic Javascript. By default, when using Object.create(), the constructor property will reflect the calling function, in this case, Bar. Thus, the right constructor is already being called.

Manually setting the constructor property allows the Bar.prototype-object to appear as if it was created by Bar rather than Foo. This is analogous to type-checking in languages like Java, where the constructor property always reflects the most specific type.

However, it's important to approach Javascript's object-oriented model with a different mindset. Instead of relying on inheritance, consider using interfaces and mixins. Additionally, checking for specific properties rather than object types is a more effective approach in Javascript.

Trying to rigidly impose classical inheritance onto Javascript's prototype-based mechanism can lead to confusion. Embracing Javascript's unique capabilities and utilizing idiomatic practices will enable you to navigate the world of Javascript's object-oriented programming with greater clarity.

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