To Parenthesize or Not: Are Parentheses Necessary When Using JavaScript's `new` Operator?

Eliminating Parentheses in Object Creation with the "new" Operator

The syntax for creating objects with the "new" operator raises questions regarding the necessity of parentheses. While it's widely assumed that parentheses are mandatory, some JavaScript expressions suggest otherwise. This discussion aims to clarify whether omitting parentheses in object creation is valid and the potential implications compared to the traditional approach with parentheses.

Valid object creation without parentheses

According to ECMAScript specifications, parentheses can be omitted when invoking the "new" operator with no arguments. David Flanagan, in his book "JavaScript the Definitive Guide," explicitly confirms this:

o = new Object;  // Optional parenthesis omitted here
d = new Date();

This simplified syntax is a special case that simplifies JavaScript grammar.

Differences between approaches

While omitting parentheses is technically valid, it's important to note that it's technically equivalent to using parentheses. There are no functional or semantic differences in object creation between the two approaches.

Recommendation

Despite the syntactic freedom, many developers prefer to use parentheses consistently, even when there are no arguments. This aligns with the general principle of using parentheses for clarity and to avoid potential confusion or syntax errors.

Additionally, using a linting tool like JSLint can help ensure consistency and flag potential errors. JSLint reports a warning when parentheses are omitted in "new" operator invocations, reinforcing the recommended practice.

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