node.js 启动应用程序时，`npm start` 和 `node app.js` 之间的区别？
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Difference between `npm start` & `node app.js`, when starting app?
提问by ReneGAED
I have installed an application using the command express new 'filename'. I have just learned that you can start an application using:
我已经使用命令安装了一个应用程序express new 'filename'。我刚刚了解到您可以使用以下方法启动应用程序：
npm start
Thus far I have used:
到目前为止，我使用过：
node app.js
to start my server. Anyone know what the difference is between the two? Thanks.
启动我的服务器。有谁知道这两者有什么区别？谢谢。
回答by Yusuf X
From the man page, npm start:
从手册页，npm start：
runs a package's "start" script, if one was provided. If no version is specified, then it starts the "active" version.
运行包的“启动”脚本（如果提供）。如果未指定版本，则它启动“活动”版本。
Admittedly, that description is completely unhelpful, and that's all it says. At least it's more documented than socket.io.
诚然，这种描述完全没有帮助，仅此而已。至少它比 socket.io 有更多的文档记录。
Anyhow, what really happens is that npm looks in your package.jsonfile, and if you have something like
无论如何，真正发生的是 npm 在您的package.json文件中查找，如果您有类似
"scripts": { "start": "coffee server.coffee" }
“脚本”：{“开始”：“咖啡服务器。咖啡”}
then it will do that. If npm can't find your start script, it defaults to:
然后它会这样做。如果 npm 找不到您的启动脚本，则默认为：
node server.js
节点服务器.js
回答by The Red Pea
The documentation has been updated. My answer has substantial changes vs the accepted answer: I wanted to reflect documentation is up-to-date, and accepted answer has a few broken links.
该文档已被更新。我的答案与接受的答案相比有很大的变化：我想反映文档是最新的，并且接受的答案有一些断开的链接。
Also, I didn't understand when the accepted answer said "it defaults to node server.js". I think the documentation clarifies the default behavior:
另外，我不明白接受的答案何时说“它默认为node server.js”。我认为文档阐明了默认行为：
npm-start
Start a package
Synopsis
npm start [-- <args>]Description
This runs an arbitrary command specified in the package's "
start" property of its "scripts" object. If no "start" property is specified on the "scripts" object, it will runnode server.js.
npm-start
开始打包
概要
npm start [-- <args>]描述
这将运行在包的
start“scripts”对象的“ ”属性中指定的任意命令。如果没有start在 "scripts" 对象上指定 " " 属性，它将运行node server.js。
In summary, running npm startcould do one of two things:
总之，跑步npm start可以做两件事之一：
npm start {command_name}: Run an arbitrary command (i.e. if such command is specified in thestartproperty of package.json'sscriptsobject)npm start: Else if nostartproperty exists (or nocommand_nameis passed): Runnode server.js, (which may not be appropriate, for example the OP doesn't haveserver.js; the OP runsnodeapp.js)- I said I would list only 2 items, but are other possibilities (i.e. error cases). For example, if there is no
package.jsonin the directory where you runnpm start, you may see an error:npm ERR! enoent ENOENT: no such file or directory, open '.\package.json'
npm start {command_name}: 运行任意命令（即，如果在startpackage.jsonscripts对象的属性中指定了此类命令）npm start：否则，如果不start存在任何属性（或没有command_name传递）：运行node server.js，（这可能不合适，例如 OP 没有server.js；OP 运行nodeapp.js）- 我说我只会列出 2 个项目，但还有其他可能性（即错误情况）。例如，如果
package.json您运行的目录中没有npm start，您可能会看到错误：npm ERR! enoent ENOENT: no such file or directory, open '.\package.json'
