Does `new` with JavaScript Function Expressions Create Static Behavior?

Function Expressions with 'new' Keyword: Unveiling the Static Nature

In JavaScript, understanding the behavior of function expressions with the 'new' keyword is crucial. Consider the following code:

var gameData = new function () {
    // Function expressions require no constructor
    this.storageAvailable = function () { ... };
};

It's important to note that the 'new' keyword in this case does not imply instantiation or allow for multiple instances to be created. Instead, it simply executes the function expression and assigns the resulting anonymous object to the 'gameData' variable.

The Misconception of Static Behavior

The concept of static behavior in C# may lead to the misconception that the function expression in JavaScript also behaves statically. However, this is inaccurate. The 'new' keyword here does not prevent the creation of a second object:

var gameData2 = new (gameData.constructor)(); // Reinstantiation is possible

Additionally, the function expression still has a constructor property pointing to the anonymous function, which can be accessed using 'gameData.constructor'. This defeats the purpose of a true static class.

Alternatives to Static Behavior

If the intent is to create a single, non-instantiable object, there are more appropriate alternatives to using function expressions with 'new':

• Object Literals: These are simple JavaScript objects with no constructor or prototype, ensuring uniqueness.
• Revealing Module Pattern: An IIFE (Immediately Invoked Function Expression) can be used to create a closure-scoped variable, returning an object with the desired properties.
• Singleton Pattern: This design pattern creates a single, controlled instance of a class that ensures all references to it point to the same object.

In conclusion, function expressions with 'new' keywords in JavaScript do not exhibit static behavior as they can be instantiated multiple times and have a public constructor property accessible through 'gameData.constructor'. For true static behavior, consider adopting alternative approaches such as object literals, revealing module patterns, or the singleton pattern.

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