package.json 中存在devDependencies和dependencies，那么他们的区别是什么呢？
devDependencies是开发中需要安装的包
dependencies是发布时需要安装的包
那么如果区分安装呢?
默认用 npm install 的时候他会安装devDependencies中的内容
如果用 npm install --production 就会安装dependencies中的内容
If you do npm config set production, then that sets the --production configuration flag for all npm commands, by setting production = true in the ~/.npmrc file.
If you do npm start --production, then it‘ll set the NODE_ENV=production environ for the start script.
If you do npm install --production then it won‘t install devDependencies locally.
devDependencies和dependencies区别
原文：http://www.cnblogs.com/zhongping/p/4526674.html