Can I Omit Parentheses When Using the JavaScript `new` Operator?

Omitting Parentheses When Creating Objects with the "new" Operator

In JavaScript, the syntax for object creation using the "new" operator typically includes parentheses. However, it has been observed that objects can be created without parentheses, as seen in the following example:

const obj = new Foo;

This raises the question whether omitting parentheses in object creation is valid and standardized.

Validity and Standardization

According to David Flanagan in "JavaScript: The Definitive Guide," it is permissible to omit parentheses when creating objects using the "new" operator if there are no arguments to be passed to the constructor. This is a special exemption within JavaScript's grammar for the "new" operator only.

Differences and Preferences

Omitting parentheses does not result in any functional differences in object creation. It mainly serves as a syntactic shortcut. However, it may not be universally accepted by code linting tools such as JSLint, which generally enforce consistent parentheses usage.

Recommendation

For clarity and adherence to best practices, it is recommended to consistently use parentheses when creating objects with the "new" operator, even in the absence of arguments to the constructor. This helps maintain uniformity and avoid potential issues with linting or code readability.

Therefore, it is considered valid to omit parentheses when creating objects with the "new" operator without arguments, but it is not a common or preferred approach.

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