javascript异常对象格式 [英] javascript exception object format

问题描述

默认情况下，当找不到文件时，Node.js会引发以下异常。

By default, Node.js throws the following exception when a file is not found.

{ [Error: ENOENT, no such file or directory 'InvalidFile']
  errno: 34,
  code: 'ENOENT',
  path: 'InvalidFile',
  syscall: 'open' }

从技术上讲，这应该是一个JavaScript对象。根据javascript对象的语义，应该有一个逗号来分隔成员元素。在这种情况下，之间没有逗号[错误：ENOENT，没有这样的文件或目录InvalidFile] 和 errno：34，。我的问题是

Technically speaking, this is supposed to be a JavaScript Object. As per the javascript object sematics, there should be a comma to separate member elements. In this case, there is no comma between [Error: ENOENT, no such file or directory 'InvalidFile'] and errno: 34,. My questions are

1. 如何构建这样的对象？

1. How do I construct an object like this?

如何在程序中访问
[错误：ENOENT，没有这样的文件或目录'InvalidFile'] 元素
？

How do I access the [Error: ENOENT, no such file or directory 'InvalidFile'] element in a program?

推荐答案

嗯，这不完全是代码。它基于JavaScript的文字语法，但仅仅是从 <$ c $生成的对象的表示c> util.inspect（） （或类似的内部函数）。

Well, it's not entirely code. It's based on JavaScript's literals syntax, but is just a representation of a the object that's generated from util.inspect() (or a similar internal function).

方括号提到类型 错误 之前的 消息 。而且，其余的是可列举的属性及其添加的值。

The square brackets mention the type of Error before its message. And, the rest is a list of enumerable properties and their values that were added to it.

自己创建它：

var error = new Error("ENOENT, no such file or directory 'InvalidFile'");
error.errno = 34;
error.code = 'ENOENT';
error.path = 'InvalidFile';
error.syscall = 'open'

console.log(error);               // uses `util.inspect()`
console.log(util.inspect(error)); // or use it directly

console.log(error.message); // "ENOENT, no such ..."
console.log(Object.prototype.toString.call(error)); // "[object Error]"

而且，对于更大的格式示例，请尝试记录一些内置模块：

And, for a larger sample of the format, try logging some built in modules:

console.log(console);

{ log: [Function],
  info: [Function],
  warn: [Function],
  error: [Function],
  dir: [Function],
  time: [Function],
  timeEnd: [Function],
  trace: [Function],
  assert: [Function],
  Console: [Function: Console] }

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