1 # Disallows unnecessary `return await` (no-return-await)
3 Using `return await` inside an `async function` keeps the current function in the call stack until the Promise that is being awaited has resolved, at the cost of an extra microtask before resolving the outer Promise. `return await` can also be used in a try/catch statement to catch errors from another function that returns a Promise.
5 You can avoid the extra microtask by not awaiting the return value, with the trade off of the function no longer being a part of the stack trace if an error is thrown asynchronously from the Promise being returned. This can make debugging more difficult.
9 This rule aims to prevent a likely common performance hazard due to a lack of understanding of the semantics of `async function`.
11 Examples of **incorrect** code for this rule:
14 async function foo() {
19 Examples of **correct** code for this rule:
22 async function foo() {
26 async function foo() {
31 async function foo() {
32 const x = await bar();
36 async function foo() {
43 In the last example the `await` is necessary to be able to catch errors thrown from `bar()`.
47 There are a few reasons you might want to turn this rule off:
49 - If you want to use `await` to denote a value that is a thenable
50 - If you do not want the performance benefit of avoiding `return await`
51 - If you want the functions to show up in stack traces (useful for debugging purposes)
55 [`async function` on MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function)
57 [`await vs return vs return await` by Jake Archibald](https://jakearchibald.com/2017/await-vs-return-vs-return-await/)