Does `return await` Hurt Performance: Fact or ESLint Fiction?

Performance Implications of return await

The ESLint rule, no-return-await, aims to discourage the use of return await expressions. However, it suggests that return await introduces performance overhead. This has sparked some confusion, given the presence of examples in official documentation that appear to contradict this notion.

Understanding return await

return await is a concise way to return the resolved value of a promise. However, it's important to clarify what it actually does and whether or not it poses any performance issues.

Performance Impact

Technically, there is no significant performance penalty associated with return await. While it does involve an additional operation, the difference is negligible. It's comparable to returning the sum of a number and zero instead of just returning the number itself.

Stylistic Concerns

From a stylistic perspective, return await is generally considered unnecessary and potentially misleading. It implies that the function is awaiting the resolution of a promise and returning its result, when in fact, the promise resolution is already implicit in the await keyword itself.

Exceptions

However, there is one exception where return await can make a practical difference. Within a try-catch block, using return await ensures that any errors thrown during the execution of the awaited promise are handled by the catch block. Without it, the errors would be ignored and not handled properly.

In conclusion, while return await does not pose any substantial performance concerns, it is generally considered poor style and can lead to potential misinterpretation. It's best to avoid using it unless necessary for error handling in try-catch blocks.

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