Is JavaScript's `new` Keyword Risky, or Are Its Benefits Worth the Potential Pitfalls?

Does JavaScript's "new" Keyword Pose a Risk?

The use of the "new" keyword in JavaScript has sparked a debate, with some claiming it poses harm. Yet, many popular JavaScript libraries rely heavily on it. Is it truly detrimental, or are the advantages it offers worth the potential pitfalls?

Advantages of Using "new"

1. Prototype Inheritance: The "new" keyword enables prototype inheritance, a simple and effective means of code reuse. Assigning methods to the constructor's prototype ensures they are shared among all instances.
2. Performance: Prototype inheritance provided by "new" enhances performance by avoiding duplication of method properties for each object. On slower machines, creating numerous objects can result in significant time and memory savings.

Disadvantages of Using "new"

1. Potential for Errors: Forgetting to use "new" can lead to code errors without warning.

Mitigating the Disadvantage

Fortunately, this disadvantage can be easily resolved by adding a code snippet to the function itself. The snippet silently corrects the omission of "new" or throws an error if strict mode is activated in ES5. This technique provides the benefits of "new" without risking code breakage.

ES5 and ES6 Enhancements

ES5 introduced strict mode, invalidating the use of "arguments.callee" in the suggested sanity check. However, ES6 introduces a safer way to detect class constructor invocation: "new.target." This check ensures safe usage of "new" even in strict mode.

Conclusion

While some argue that the "new" keyword is harmful, its benefits outweigh the risks if used correctly. With proper error handling and hygiene, it is possible to leverage the advantages of prototype inheritance and performance optimization offered by "new" without sacrificing code reliability. ES6 provides additional tools to further mitigate potential errors.

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