在 JavaScript 中将错误对象转换为字符串

在 JavaScript 中将错误对象转换为字符串

Convert an Error Object to a String in JavaScript

要将错误对象转换为字符串，请访问该message对象的属性，例如err.message. 该message属性是对错误发生原因的人类可读描述。

const err = new Error('Something went wrong');

console.log(err.message); // 👉️ "Something went wrong"

当使用
Error()
构造函数创建错误时，我们可以访问错误的
message
属性以获取错误发生原因的人类可读字符串。

最佳实践是始终使用错误构造函数抛出错误，或者在需要添加功能时扩展它。

throw new Error('Something went wrong');

Promise.reject(new Error('Something went wrong'));

即使在拒绝承诺时，您也可以将错误传递给reject()方法。

如果你必须处理来自第三方包的错误的奇怪实现，你应该检查错误值是否是一个对象并且具有message
避免访问不存在的属性的属性。

const err = null;

if (typeof err === 'object' && err !== null && 'message' in err) {
  const message = err.message;
  console.log(message);
}

我们的if条件使用逻辑与 (&&) 运算符，因此if要运行该块，必须满足所有条件。

Then we check if the variable is not equal to null. Unfortunately, if you
check the type of null – console.log(typeof null), you will get an "object"
value back, so we have to make sure the value is not null.

Then we know we can safely access the message property on the object.

If that doesn’t work, as a last resort, you can try to access the toString()
method on the error object.

Some third party packages throw error objects that implement the toString()
method.

const err = null;

if (typeof err === 'object' && err !== null && 'toString' in err) {
  const message = err.toString();
  console.log(message);
}

If that doesn’t work either, you have to console.log the error object and
investigate what properties and methods it implements.