> TypeScript：示例是.ts，您需要运行一个编译器步骤来将它们导入到.js中，这可以使用Node.js和NPM轻松完成(加上它是一种轻松获取打字文件的方法);
> Web服务器：从“真实的”即时轻网络服务器为您提供的Angular SPA可以避免使用file：//链接检查您的站点时遇到的一些令人讨厌的问题。

“快速入门”指南本身也在继续提及一些更具体的原因：

Here’s what these scripts do:

• npm start – runs the compiler and a server at the same time,both in “watch mode”

• npm run tsc – runs the TypeScript compiler once

• npm run tsc:w – runs the TypeScript compiler in watch mode; the process keeps running,awaiting changes to TypeScript files and re-compiling when it sees them

• npm run lite – runs the lite-server,a light-weight,static file server with excellent support for Angular apps that use routing

• npm run typings – runs the typings tool separately

• npm run postinstall – called by npm automatically after it successfully completes package installation. This script installs the TypeScript definition files defined in typings.json

您还可以看看the Quickstart source，并进一步深入了解需要NPM的地方。