Should You Use the 'new' Keyword in JavaScript?

The Controversial "new" Keyword in JavaScript

Douglas Crockford's assertion that the "new" keyword should be avoided in JavaScript has sparked a lively debate. While the keyword has its advantages, concerns about potential misuse have led some to question its necessity.

Advantages of Using "new"

• Prototype inheritance: The "new" keyword facilitates prototype inheritance, a fundamental technique in JavaScript for code reuse and object-oriented programming.
• Performance: By centralizing method assignments to the prototype, "new" improves code efficiency, particularly when creating numerous objects.

Drawback of Using "new"

• Accidental omission: If the "new" keyword is inadvertently omitted, the code will silently break without providing any indication.

Mitigating the Disadvantage

To overcome the potential issue of accidental omission, various solutions have been proposed:

• Self-correction function: Add code to the function that checks if the "new" keyword was used. If not, the function can silently instantiate the object.
• Assertion: Include an assertion to check for the "new" keyword and alert the developer if it was omitted.
• Runtime exception: Raise a runtime exception to alert the developer of the omission.

ES5 and Strict Mode

In ES5 strict mode, the workaround of using "arguments.callee" is no longer valid, requiring alternative solutions.

ES6 and Safe "new"

ES6 introduces Classes as a safer alternative to the "new" keyword, ensuring that constructors are invoked only with "new."

Conclusion

With proper care and the use of mitigating techniques, the "new" keyword can be used effectively in JavaScript without the potential for harm raised by Crockford. Developers have a range of options to ensure that their code is resilient against accidental omissions and can leverage the advantages of "new" to enhance code reusability and performance.

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