custom-error-definition.md

Enforce correct Error subclassing

Enforces the only valid way of Error subclassing. It works with any super class that ends in Error.

Fail

class CustomError extends Error {
	constructor(message) {
		super(message);
		this.message = message;
		this.name = 'CustomError';
	}
}

The this.message assignment is useless as it's already set via the super() call.

class CustomError extends Error {
	constructor(message) {
		super();
		this.message = message;
		this.name = 'CustomError';
	}
}

Pass the error message to super() instead of setting this.message.

class CustomError extends Error {
	constructor(message) {
		super(message);
	}
}

No name property set. The name property is needed so the error shows up as [CustomError: foo] and not [Error: foo].

class CustomError extends Error {
	constructor(message) {
		super(message);
		this.name = this.constructor.name;
	}
}

Use a string literal to set the name property as it will not change after minifying.

class CustomError extends Error {
	constructor(message) {
		super(message);
		this.name = 'MyError';
	}
}

The name property should be set to the class name.

class foo extends Error {
	constructor(message) {
		super(message);
		this.name = 'foo';
	}
}

The class name is invalid. It should be capitalized and end with Error. In this case it should be FooError.

Pass

class CustomError extends Error {
	constructor(message) {
		super(message);
		this.name = 'CustomError';
	}
}

class CustomError extends Error {
	constructor() {
		super('My custom error');
		this.name = 'CustomError';
	}
}

class CustomError extends TypeError {
	constructor() {
		super();
		this.name = 'CustomError';
	}
}