E0174: functions/methods should not have '=>'

Classes and object literals can contain methods. It is a syntax error to write => before the method's body:

class Dog {
  bark() => {
    console.log("woof");
  }
}

class Downloader {
  okStatuses = [200];

  async download(url) {
    return await axios.get(url, {
      responseType: "json",
      validateStatus(status) => {
        return this.okStatuses.includes(status);
      },
    });
  }
}

To fix this error, remove the => to create a valid method:

class Dog {
  bark() {
    console.log("woof");
  }
}

Alternatively, in an object literal, create an arrow function instead of a method by adding : after the method name:

class Downloader {
  okStatuses = [200];

  async download(url) {
    return await axios.get(url, {
      responseType: "json",
      validateStatus: (status) => {
        return this.okStatuses.includes(status);
      },
    });
  }
}

Introduced in quick-lint-js version 0.5.0.

Documentation for other errors