JS.TS.PROMISE.FUNCTION.ASYNC

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.

Rule Details

Examples of code for this rule

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Incorrect

const arrowFunctionReturnsPromise = () => Promise.resolve('value');

function functionReturnsPromise() {
  return Promise.resolve('value');
}

Correct

const arrowFunctionReturnsPromise = async () => Promise.resolve('value');

async function functionReturnsPromise() {
  return Promise.resolve('value');
}

Options

Options may be provided as an object with:

• allowAny to indicate that any or unknown shouldn't be considered Promises (true by default).
• allowedPromiseNames to indicate any extra names of classes or interfaces to be considered Promises when returned.

In addition, each of the following properties may be provided, and default to true:

• checkArrowFunctions
• checkFunctionDeclarations
• checkFunctionExpressions
• checkMethodDeclarations

{
  "@typescript-eslint/promise-function-async": [
    "error",
    {
      "allowedPromiseNames": ["Thenable"],
      "checkArrowFunctions": true,
      "checkFunctionDeclarations": true,
      "checkFunctionExpressions": true,
      "checkMethodDeclarations": true
    }
  ]
}