出于某种原因,在下面的代码段中,构造函数委托似乎不起作用:

function NotImplementedError() { 
  Error.apply(this, arguments); 
}
NotImplementedError.prototype = new Error();

var nie = new NotImplementedError("some message");
console.log("The message is: '"+nie.message+"'")

运行该命令得到的消息是:"。有什么想法,为什么,或者是否有更好的方法来创建一个新的错误子类?是否有一个问题,应用到本机错误构造函数,我不知道?


当前回答

function InvalidValueError(value, type) {
    this.message = "Expected `" + type.name + "`: " + value;
    var error = new Error(this.message);
    this.stack = error.stack;
}
InvalidValueError.prototype = new Error();
InvalidValueError.prototype.name = InvalidValueError.name;
InvalidValueError.prototype.constructor = InvalidValueError;

其他回答

我只需要实现这样的东西,发现堆栈在我自己的错误实现中丢失了。我要做的是创建一个虚拟错误,并从中检索堆栈:

My.Error = function (message, innerException) {
    var err = new Error();
    this.stack = err.stack; // IMPORTANT!
    this.name = "Error";
    this.message = message;
    this.innerException = innerException;
}
My.Error.prototype = new Error();
My.Error.prototype.constructor = My.Error;
My.Error.prototype.toString = function (includeStackTrace) {
    var msg = this.message;
    var e = this.innerException;
    while (e) {
        msg += " The details are:\n" + e.message;
        e = e.innerException;
    }
    if (includeStackTrace) {
        msg += "\n\nStack Trace:\n\n" + this.stack;
    }
    return msg;
}

这是最快的方法:

    let thisVar = false

    if (thisVar === false) {
            throw new Error("thisVar is false. It should be true.")
    }

另一种替代方法可能并不适用于所有环境。至少可以保证它在nodejs 0.8中工作 这种方法使用了一种非标准的方法来修改内部原型道具

function myError(msg){ 
      var e = new Error(msg); 
      _this = this; 
      _this.__proto__.__proto__ = e;
}

这是我的实现:

class HttpError extends Error {
  constructor(message, code = null, status = null, stack = null, name = null) {
    super();
    this.message = message;
    this.status = 500;

    this.name = name || this.constructor.name;
    this.code = code || `E_${this.name.toUpperCase()}`;
    this.stack = stack || null;
  }

  static fromObject(error) {
    if (error instanceof HttpError) {
      return error;
    }
    else {
      const { message, code, status, stack } = error;
      return new ServerError(message, code, status, stack, error.constructor.name);
    }
  }

  expose() {
    if (this instanceof ClientError) {
      return { ...this };
    }
    else {
      return {
        name: this.name,
        code: this.code,
        status: this.status,
      }
    }
  }
}

class ServerError extends HttpError {}

class ClientError extends HttpError { }

class IncorrectCredentials extends ClientError {
  constructor(...args) {
    super(...args);
    this.status = 400;
  }
}

class ResourceNotFound extends ClientError {
  constructor(...args) {
    super(...args);
    this.status = 404;
  }
}

示例用法#1:

app.use((req, res, next) => {
  try {
    invalidFunction();
  }
  catch (err) {
    const error = HttpError.fromObject(err);
    return res.status(error.status).send(error.expose());
  }
});

示例用法#2:

router.post('/api/auth', async (req, res) => {
  try {
    const isLogged = await User.logIn(req.body.username, req.body.password);

    if (!isLogged) {
      throw new IncorrectCredentials('Incorrect username or password');
    }
    else {
      return res.status(200).send({
        token,
      });
    }
  }
  catch (err) {
    const error = HttpError.fromObject(err);
    return res.status(error.status).send(error.expose());
  }
});

我喜欢这样做:

利用name,使toString()抛出"{code}: {message}" 将相同的东西返回给super,这样在stacktrace中就会显示相同的内容 将代码附加到错误。在代码中检查/解析代码比检查消息(例如,您可能希望本地化消息)更好 将消息附加到错误。message作为error.toString()的替代

class AppException extends Error { constructor(code, message) { const fullMsg = message ? `${code}: ${message}` : code; super(fullMsg); this.name = code; this.code = code; this.message = fullMsg; } toString() { return this.message; } } // Just a code try { throw new AppException('FORBIDDEN'); } catch(e) { console.error(e); console.error(e.toString()); console.log(e.code === 'FORBIDDEN'); } // A code and a message try { throw new AppException('FORBIDDEN', 'You don\'t have access to this page'); } catch(e) { console.error(e); console.error(e.toString()); console.log(e.code === 'FORBIDDEN'); }