typescript/only-throw-error Pedantic
What it does
This rule disallows throwing non-Error values.
Why is this bad?
It's considered good practice to only throw Error objects (or subclasses of Error). This is because Error objects automatically capture a stack trace, which is useful for debugging. Additionally, some tools and environments expect thrown values to be Error objects.
Examples
Examples of incorrect code for this rule:
ts
throw "error"; // throwing string
throw 42; // throwing number
throw true; // throwing boolean
throw { message: "error" }; // throwing plain object
throw null; // throwing null
throw undefined; // throwing undefined
const error = "Something went wrong";
throw error; // throwing non-Error variableExamples of correct code for this rule:
ts
throw new Error("Something went wrong");
throw new TypeError("Invalid type");
throw new RangeError("Value out of range");
// Custom Error subclasses
class CustomError extends Error {
constructor(message: string) {
super(message);
this.name = "CustomError";
}
}
throw new CustomError("Custom error occurred");
// Variables that are Error objects
const error = new Error("Error message");
throw error;Configuration
This rule accepts a configuration object with the following properties:
allow
type: array
default: []
An array of type or value specifiers for additional types that are allowed to be thrown. Use this to allow throwing custom error types.
allow[n]
type: string
Type or value specifier for matching specific declarations
Supports four types of specifiers:
- String specifier (deprecated): Universal match by name
json
"Promise"- File specifier: Match types/values declared in local files
json
{ "from": "file", "name": "MyType" }
{ "from": "file", "name": ["Type1", "Type2"] }
{ "from": "file", "name": "MyType", "path": "./types.ts" }- Lib specifier: Match TypeScript built-in lib types
json
{ "from": "lib", "name": "Promise" }
{ "from": "lib", "name": ["Promise", "PromiseLike"] }- Package specifier: Match types/values from npm packages
json
{ "from": "package", "name": "Observable", "package": "rxjs" }
{ "from": "package", "name": ["Observable", "Subject"], "package": "rxjs" }allowThrowingAny
type: boolean
default: true
Whether to allow throwing values typed as any.
allowThrowingUnknown
type: boolean
default: true
Whether to allow throwing 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/only-throw-errorjson
{
"rules": {
"typescript/only-throw-error": "error"
}
}