NodeJS之NPM包管理器的使用

NPM包管理器概述

NPM（Node Package Manager，即：node包管理器）是nodeJS的一个程序包管理和分发的管理工具，npm完全用JavaScript写成，它可以让全世界与Web前端相关开发者共享代码，非常方便的使用各种插件、库和框架，无需再到处去搜寻需要用到的这些程序。

NPM的安装

NPM原本是Node的单独项目，现已被集成至NodeJS中，只要安装了NodeJS就可以使用NPM了。

package.json

NPM的操作与pakage.json密切相关，NPM实际维护了一个package.json的文件，其内容格式如下所示,示例为一个Vue项目的文件。

{
  "name": "nodeweb",
  "version": "1.0.0",
  "description": "A Vue.js project",
  "author": "** <**@piesat.cn>",
  "private": true,
  "scripts": {
    "dev": "webpack-dev-server --inline --progress --config build/webpack.dev.conf.js",
    "start": "npm run dev",
    "build": "node build/build.js"
  },
  "dependencies": {
    "cesium": "^1.67.0",
    "view-design": "^4.1.3",
    "vue": "^2.5.2"
  },
  "devDependencies": {
    "autoprefixer": "^7.1.2",
    "babel-core": "^6.22.1",
    "babel-helper-vue-jsx-merge-props": "^2.0.3",
    "babel-loader": "^7.1.1",
    "babel-plugin-syntax-jsx": "^6.18.0",
    "babel-plugin-transform-runtime": "^6.22.0",
    "babel-plugin-transform-vue-jsx": "^3.5.0",
    "babel-preset-env": "^1.3.2",
    "babel-preset-stage-2": "^6.22.0",
    "chalk": "^2.0.1",
    "copy-webpack-plugin": "^4.0.1",
    "css-loader": "^0.28.0",
    "extract-text-webpack-plugin": "^3.0.0",
    "file-loader": "^1.1.4",
    "friendly-errors-webpack-plugin": "^1.6.1",
    "html-webpack-plugin": "^2.30.1",
    "node-notifier": "^5.1.2",
    "optimize-css-assets-webpack-plugin": "^3.2.0",
    "ora": "^1.2.0",
    "portfinder": "^1.0.13",
    "postcss-import": "^11.0.0",
    "postcss-loader": "^2.0.8",
    "postcss-url": "^7.2.1",
    "rimraf": "^2.6.0",
    "semver": "^5.3.0",
    "shelljs": "^0.7.6",
    "uglifyjs-webpack-plugin": "^1.1.1",
    "url-loader": "^0.5.8",
    "vue-loader": "^13.3.0",
    "vue-style-loader": "^3.0.1",
    "vue-template-compiler": "^2.5.2",
    "webpack": "^3.6.0",
    "webpack-bundle-analyzer": "^2.9.0",
    "webpack-dev-server": "^2.9.1",
    "webpack-merge": "^4.1.0"
  },
  "engines": {
    "node": ">= 6.0.0",
    "npm": ">= 3.0.0"
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not ie <= 8"
  ]
}

• scripts
  使用npm run 命令可以快速运行scripts中的脚本，完全的自由控制。
• dependencies
  为了项目整洁，此项下一般存放项目中实际发布时要用的包的依赖信息。
• devDependencies
  存放开发时的一切辅助用的包，如webpack。

NPM常用命令

1. 安装cnpm

npm install -g cnpm --registry=https://registry.npm.taobao.org

2. 全局安装模块

npm install -g webpack 

3. 安装开发版模块

npm install webpack --save-dev
或
npm i webpack -D

4. 安装package.json中的包

cnpm install