Require using Error objects as Promise rejection reasons
It is considered good practice to only pass instances of the built-in Error object to the reject() function for user-defined errors in Promises. Error objects automatically store a stack trace, which can be used to debug an error by determining where it came from. If a Promise is rejected with a non-Error value, it can be difficult to determine where the rejection occurred.
This rule aims to ensure that Promises are only rejected with Error objects.
This rule takes one optional object argument:
allowEmptyReject: true (false by default) allows calls to Promise.reject() with no arguments.Examples of incorrect code for this rule:
/*eslint prefer-promise-reject-errors: "error"*/
Promise.reject("something bad happened");
Promise.reject(5);
Promise.reject();
new Promise(function(resolve, reject) {
reject("something bad happened");
});
new Promise(function(resolve, reject) {
reject();
});
Examples of correct code for this rule:
/*eslint prefer-promise-reject-errors: "error"*/
Promise.reject(new Error("something bad happened"));
Promise.reject(new TypeError("something bad happened"));
new Promise(function(resolve, reject) {
reject(new Error("something bad happened"));
});
var foo = getUnknownValue();
Promise.reject(foo);
Examples of correct code for this rule with the allowEmptyReject: true option:
/*eslint prefer-promise-reject-errors: ["error", {"allowEmptyReject": true}]*/
Promise.reject();
new Promise(function(resolve, reject) {
reject();
});
Due to the limits of static analysis, this rule cannot guarantee that you will only reject Promises with Error objects. While the rule will report cases where it can guarantee that the rejection reason is clearly not an Error, it will not report cases where there is uncertainty about whether a given reason is an Error. For more information on this caveat, see the similar limitations in the no-throw-literal rule.
To avoid conflicts between rules, this rule does not report non-error values used in throw statements in async functions, even though these lead to Promise rejections. To lint for these cases, use the no-throw-literal rule.
If you’re using custom non-error values as Promise rejection reasons, you can turn off this rule.
This rule was introduced in ESLint v3.14.0.
© OpenJS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/latest/rules/prefer-promise-reject-errors