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附錄：Error 對(duì)象屬性命名約定
強(qiáng)烈建議你在發(fā)生錯(cuò)誤的時(shí)候用這些名字來(lái)保持和Node核心以及Node插件的一致。這些大部分不會(huì)和某個(gè)給定的異常對(duì)應(yīng)，但是出現(xiàn)疑問(wèn)的時(shí)候，你應(yīng)該包含任何看起來(lái)有用的信息，即從編程上也從自定義的錯(cuò)誤消息上。【表】。
| Property name | Intended use |
|---|---|
| localHostname | the local DNS hostname (e.g., that you're accepting connections at) |
| localIp | the local IP address (e.g., that you're accepting connections at) |
| localPort | the local TCP port (e.g., that you're accepting connections at) |
| remoteHostname | the DNS hostname of some other service (e.g., that you tried to connect to) |
| remoteIp | the IP address of some other service (e.g., that you tried to connect to) |
| remotePort | the port of some other service (e.g., that you tried to connect to) |
| path | the name of a file, directory, or Unix Domain Socket (e.g., that you tried to open) |
| srcpath | the name of a path used as a source (e.g., for a rename or copy) |
| dstpath | the name of a path used as a destination (e.g., for a rename or copy) |
| hostname | a DNS hostname (e.g., that you tried to resolve) |
| ip | an IP address (e.g., that you tried to reverse-resolve) |
| propertyName | an object property name, or an argument name (e.g., for a validation error) |
| propertyValue | an object property value (e.g., for a validation error) |
| syscall | the name of a system call that failed |
| errno | the symbolic value of errno (e.g., "ENOENT"). Do not use this for errors that don't actually set the C value of errno.Use "name" to distinguish between types of errors. |
腳注
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人們有的時(shí)候會(huì)這么寫(xiě)代碼，他們想要在出現(xiàn)異步錯(cuò)誤的時(shí)候調(diào)用 callback 并把錯(cuò)誤作為參數(shù)傳遞。他們錯(cuò)誤地認(rèn)為在自己的回調(diào)函數(shù)（傳遞給?
doSomeAsynchronousOperation?的函數(shù)）里throw?一個(gè)異常，會(huì)被外面的catch代碼塊捕獲。try/catch和異步函數(shù)不是這么工作的。回憶一下，異步函數(shù)的意義就在于被調(diào)用的時(shí)候myApiFunc函數(shù)已經(jīng)返回了。這意味著try代碼塊已經(jīng)退出了。這個(gè)回調(diào)函數(shù)是由Node直接調(diào)用的，外面并沒(méi)有try的代碼塊。如果你用這個(gè)反模式，結(jié)果就是拋出異常的時(shí)候，程序崩潰了。 -
在JavaScript里，拋出一個(gè)不屬于Error的參數(shù)從技術(shù)上是可行的，但是應(yīng)該被避免。這樣的結(jié)果使獲得調(diào)用堆棧沒(méi)有可能，代碼也無(wú)法檢查”name“屬性，或者其它任何能夠說(shuō)明哪里有問(wèn)題的屬性。
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操作失敗和程序員的失誤這一概念早在NodeJS之前就已經(jīng)存在存在了。不嚴(yán)格地對(duì)應(yīng)者Java里的checked和unchecked異常，雖然操作失敗被認(rèn)為是無(wú)法避免的，比如 OutOfMemeoryError，被歸為uncheked異常。在C語(yǔ)言里有對(duì)應(yīng)的概念，普通異常處理和使用斷言。維基百科上關(guān)于斷言的的文章也有關(guān)于什么時(shí)候用斷言什么時(shí)候用普通的錯(cuò)誤處理的類似的解釋。
- 如果這看起來(lái)非常具體，那是因?yàn)槲覀冊(cè)诋a(chǎn)品環(huán)境中遇到這樣過(guò)這樣的問(wèn)題。這真的很可怕。
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