一：package.json文件详解
管理你本地安装的npm包 。定义了这个项目所需要的各种模块，以及项目的配置信息（比如名称、版本、许可证等元数据）。npm install命令根据这个配置文件，自动下载所需的模块，也就是配置项目所需的运行和开发环境。
{ "name": "vue2-manage", "version": "1.0.1", "description": "vue2-manage", "author": "cangdu <1264889788@qq.com>", "license": "GPL", "private": true, "scripts": { "dev": "cross-env NODE_ENV=online node build/dev-server.js", "local": "cross-env NODE_ENV=local node build/dev-server.js", "build": "node build/build.js", "unit": "cross-env BABEL_ENV=test karma start test/unit/karma.conf.js --single-run", "e2e": "node test/e2e/runner.js", "test": "npm run unit && npm run e2e", "lint": "eslint --ext .js,.vue src test/unit/specs test/e2e/specs" }, "dependencies": { "echarts": "^3.5.4", "element-ui": "^1.2.9", "time-formater": "^1.0.1", "vue": "^2.2.6", "vue-quill-editor": "^2.2.1", "vue-router": "^2.3.1", "vue-simplemde": "^0.3.8", "vuex": "^2.3.1" }, "devDependencies": { "autoprefixer": "^6.7.2", "babel-core": "^6.22.1", "babel-eslint": "^7.1.1", "babel-loader": "^6.2.10", "babel-plugin-component": "^0.9.1", "babel-plugin-istanbul": "^4.1.1", "babel-plugin-transform-runtime": "^6.22.0", "babel-polyfill": "^6.23.0", "babel-preset-env": "^1.3.2", "babel-preset-stage-2": "^6.22.0", "babel-register": "^6.22.0", "babel-runtime": "^6.23.0", "chai": "^3.5.0", "chalk": "^1.1.3", "chromedriver": "^2.27.2", "connect-history-api-fallback": "^1.3.0", "copy-webpack-plugin": "^4.0.1", "cross-env": "^4.0.0", "cross-spawn": "^5.0.1", "css-loader": "^0.28.0", "eslint": "^3.19.0", "eslint-config-standard": "^6.2.1", "eslint-friendly-formatter": "^2.0.7", "eslint-loader": "^1.7.1", "eslint-plugin-html": "^2.0.0", "eslint-plugin-promise": "^3.4.0", "eslint-plugin-standard": "^2.0.1", "eventsource-polyfill": "^0.9.6", "express": "^4.14.1", "extract-text-webpack-plugin": "^2.0.0", "file-loader": "^0.11.1", "friendly-errors-webpack-plugin": "^1.1.3", "html-webpack-plugin": "^2.28.0", "http-proxy-middleware": "^0.17.3", "inject-loader": "^3.0.0", "karma": "^1.4.1", "karma-coverage": "^1.1.1", "karma-mocha": "^1.3.0", "karma-phantomjs-launcher": "^1.0.2", "karma-phantomjs-shim": "^1.4.0", "karma-sinon-chai": "^1.3.1", "karma-sourcemap-loader": "^0.3.7", "karma-spec-reporter": "0.0.30", "karma-webpack": "^2.0.2", "less": "^2.7.2", "less-loader": "^4.0.3", "lolex": "^1.5.2", "mocha": "^3.2.0", "nightwatch": "^0.9.12", "opn": "^4.0.2", "optimize-css-assets-webpack-plugin": "^1.3.0", "ora": "^1.2.0", "phantomjs-prebuilt": "^2.1.14", "rimraf": "^2.6.0", "selenium-server": "^3.0.1", "semver": "^5.3.0", "shelljs": "^0.7.6", "sinon": "^2.1.0", "sinon-chai": "^2.8.0", "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" }, "engines": { "node": ">= 4.0.0", "npm": ">= 3.0.0" }, "browserslist": [ "> 1%", "last 2 versions", "not ie <= 8" ] }
scripts字段:
指定了运行脚本命令的npm命令行缩写;
比如： dev : "dev": "cross-env NODE_ENV=online node build/dev-server.js"
dependencies字段:
指定了项目运行所依赖的模块.
devDependencies字段：
指定项目开发所需要的模块。
engines字段：
指明了该模块运行的平台，比如 Node 的某个版本或者浏览器。
2 package.json文件生成
package.json文件可以手工编写，也可以使用npm init命令自动生成；
这个命令采用互动方式，要求用户回答一些问题，然后在当前目录生成一个基本的package.json文件。所有问题之中，只有项目名称（name）和项目版本（version）是必填的，其他都是选填的。
有了package.json文件，直接使用npm install命令，就会在当前目录中安装所需要的模块。
3 package.json是给nodejs用的, 还是npm
npm在package.json文件中管理项目的依赖项以及项目的元数据。
node执行js中require的时候，也会根据package.json中的依赖项查找。