typescript/prefer-promise-reject-errors Pedantic
What it does
This rule enforces passing an Error object to Promise.reject().
Why is this bad?
It's considered good practice to only reject promises with Error objects. This is because Error objects automatically capture a stack trace, which is useful for debugging. Additionally, some tools and environments expect rejection reasons to be Error objects.
Examples
Examples of incorrect code for this rule:
ts
Promise.reject("error"); // rejecting with string
Promise.reject(42); // rejecting with number
Promise.reject(true); // rejecting with boolean
Promise.reject({ message: "error" }); // rejecting with plain object
Promise.reject(null); // rejecting with null
Promise.reject(); // rejecting with undefined
const error = "Something went wrong";
Promise.reject(error); // rejecting with non-Error variableExamples of correct code for this rule:
ts
Promise.reject(new Error("Something went wrong"));
Promise.reject(new TypeError("Invalid type"));
Promise.reject(new RangeError("Value out of range"));
// Custom Error subclasses
class CustomError extends Error {
constructor(message: string) {
super(message);
this.name = "CustomError";
}
}
Promise.reject(new CustomError("Custom error occurred"));
// Variables that are Error objects
const error = new Error("Error message");
Promise.reject(error);Configuration
This rule accepts a configuration object with the following properties:
allowEmptyReject
type: boolean
default: false
Whether to allow calling Promise.reject() with no arguments.
allowThrowingAny
type: boolean
default: false
Whether to allow rejecting Promises with values typed as any.
allowThrowingUnknown
type: boolean
default: false
Whether to allow rejecting Promises with values typed as unknown.
How to use
To enable this rule in the CLI or using the config file, you can use:
bash
oxlint --type-aware --deny typescript/prefer-promise-reject-errorsjson
{
"rules": {
"typescript/prefer-promise-reject-errors": "error"
}
}