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promise-function-async

Requires any function or method that returns a Promise to be marked 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.

Attributes​

  • Included in configs
    • ✅ Recommended
    • 🔒 Strict
  • Fixable
    • 🔧 Automated Fixer
    • 🛠 Suggestion Fixer
  • 💭 Requires type information

Rule Details​

Examples of code for this rule

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

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
    }
  ]
}