npm i 插件   ,会把插件安装到node_modules目录中,不会修改package.json,

npm i 插件 --save  ,项目发布上线之后还会依赖用到的插件,没有这些插件,项目不能运行

自动更改package.json  

"dependencies": {
"axios": "^0.16.1",
"vue": "^2.2.6",
"vue-infinite-scroll": "^2.0.1",
"vue-lazyload": "^1.0.5",
"vue-resource": "^1.3.1",
"vue-router": "^2.3.1",
"vuex": "^2.3.1"
},


npm i 插件 --save-dev ,安装到开发依赖中,项目上线之后不会用到的插件,例如'babel-loader',项目解析完发布
自动更改package.json  
"devDependencies": {
"autoprefixer": "^6.7.2",
"babel-cli": "^6.24.1",
"babel-core": "^6.22.1",
"babel-loader": "^6.2.10",
"babel-plugin-transform-runtime": "^6.22.0",
"babel-preset-env": "^1.3.2",
"babel-preset-stage-2": "^6.22.0",
"babel-register": "^6.22.0",
"url-loader": "^0.5.8",
"vue-loader": "^11.3.4",
"vue-style-loader": "^2.0.5",
"vue-template-compiler": "^2.2.6",
"webpack": "^2.3.3",
"webpack-bundle-analyzer": "^2.2.1",
"webpack-dev-middleware": "^1.10.0",
"webpack-hot-middleware": "^2.18.0",
"webpack-merge": "^4.1.0"
},