NPX是一个用于在新项目中创建和执行某些特性的工具 NPM是包含所有库的包管理器

NPX:

从https://www.futurehosting.com/blog/npx-makes-life-easier-for-node-developers-plus-node-vulnerability-news/:

Web developers can have dozens of projects on their development machines, and each project has its own particular set of npm-installed dependencies. A few years back, the usual advice for dealing with CLI applications like Grunt or Gulp was to install them locally in each project and also globally so they could easily be run from the command line. But installing globally caused as many problems as it solved. Projects may depend on different versions of command line tools, and polluting the operating system with lots of development-specific CLI tools isn’t great either. Today, most developers prefer to install tools locally and leave it at that. Local versions of tools allow developers to pull projects from GitHub without worrying about incompatibilities with globally installed versions of tools. NPM can just install local versions and you’re good to go. But project specific installations aren’t without their problems: how do you run the right version of the tool without specifying its exact location in the project or playing around with aliases? That’s the problem npx solves. A new tool included in NPM 5.2, npx is a small utility that’s smart enough to run the right application when it’s called from within a project. If you wanted to run the project-local version of mocha, for example, you can run npx mocha inside the project and it will do what you expect. A useful side benefit of npx is that it will automatically install npm packages that aren’t already installed. So, as the tool’s creator Kat Marchán points out, you can run npx benny-hill without having to deal with Benny Hill polluting the global environment. If you want to take npx for a spin, update to the most recent version of npm.

npx是一个npm包运行器(x可能代表eXecute)。使用npx的一种常见方法是下载并临时运行一个包或进行试用。

Create-react-app是一个NPM包，预计在项目的生命周期中只运行一次。因此，最好使用npx在一个步骤中安装和运行它。

正如主页https://www.npmjs.com/package/npx中提到的，默认情况下，npx可以在PATH或node_modules/.bin中运行命令。

注意: 通过深入研究，我们可以发现create-react-app指向一个在节点环境中执行的Javascript文件(在Linux系统中可能是/usr/lib/node_modules/create-react-app/index.js)。这只是一个执行一些检查的全局工具。实际的设置由react-scripts完成，其最新版本安装在项目中。更多信息请参考https://github.com/facebook/create-react-app。

这里有一个NPX的例子:NPX cowsay hello

如果您将其输入到bash终端，您将看到结果。这样做的好处是npx临时安装了cowsay。没有包装污染，因为cowsay不是永久安装的。这对于想要避免包装污染的一次性包装非常有用。

正如在其他回答中提到的，npx在运行前需要安装并配置包的情况下也非常有用(使用npm)。例如，不用使用npm来安装和配置json。包文件，然后调用配置的运行命令，只需使用NPX代替。一个真实的例子: create-react-app my-app

NPM是用来安装包的工具，NPX是用来执行包的工具。 如果你想通过npm运行一个包，那么你必须在你的包中指定这个包。并在本地安装它。 npx-一个包不需要安装就可以执行。它是一个npm包运行器，所以如果任何包还没有安装，它会自动安装它们。

另一方面，npx使用的包并不是全局安装的，所以你必须担心长期的污染。