如何处理 404 响应？

在 Express 中，404 响应不是错误的结果，因此错误处理程序中间件不会捕获它们。这种行为是因为 404 响应只是表明没有额外的工作要做；也就是说，Express 已经执行了所有的中间件函数和路由，发现没有一个响应。您需要做的就是在堆栈的最底部（在所有其他函数下方）添加一个中间件函数来处理 404 响应：

In Express, 404 responses are not the result of an error, so the error-handler middleware will not capture them. This behavior is because a 404 response simply indicates the absence of additional work to do; in other words, Express has executed all middleware functions and routes, and found that none of them responded. All you need to do is add a middleware function at the very bottom of the stack (below all other functions) to handle a 404 response:

app.use((req, res, next) => {
  res.status(404).send("Sorry can't find that!")
})

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