promise-function-async
Require any function or method that returns a Promise to be marked async.
🛠
Some problems reported by this rule are automatically fixable by the --fix
ESLint command line option.
💭
This rule requires type information to run.
Ensures that each function is only capable of:
- returning a rejected promise, or
- throwing an Error object.
In contrast, non-async
Promise
- returning functions are technically capable of either.
Code that handles the results of those functions will often need to handle both cases, which can get complex.
This rule's practice removes a requirement for creating code to handle both cases.
.eslintrc.cjs
module.exports = {
"rules": {
"@typescript-eslint/promise-function-async": "warn"
}
};
Examples
Examples of code for this rule
- ❌ Incorrect
- ✅ Correct
const arrowFunctionReturnsPromise = () => Promise.resolve('value');
function functionReturnsPromise() {
return Promise.resolve('value');
}
const arrowFunctionReturnsPromise = async () => Promise.resolve('value');
async function functionReturnsPromise() {
return Promise.resolve('value');
}
Options
This rule accepts an options object with the following properties:
interface Options {
/**
* Whether to consider `any` and `unknown` to be Promises.
*/
allowAny?: boolean;
/**
* Any extra names of classes or interfaces to be considered Promises.
*/
allowedPromiseNames?: string[];
checkArrowFunctions?: boolean;
checkFunctionDeclarations?: boolean;
checkFunctionExpressions?: boolean;
checkMethodDeclarations?: boolean;
}
const defaultOptions: Options = [
{
allowAny: true,
allowedPromiseNames: [],
checkArrowFunctions: true,
checkFunctionDeclarations: true,
checkFunctionExpressions: true,
checkMethodDeclarations: true,
},
];