初探 npm 脚本
· 2 min read ·
Vue CSS JavaScript Node.js Webpack SourceMap
一 npm脚本配置
npm脚本在我们日常工作中用到的还是非常多的，如果大家用webpack作为打包工具的话，相信npm run dev/bulid 之类的命令大家一定都使用的非常多了。那么为什么只需要输入npm run dev就能开启一个虚拟服务器？为什么run build就能构建项目呢？相信有很多同学会和我一样存在着些许疑问。下面我们就来看一看npm run dev/bulid等命令到底是个什么东西？
1.1 package.json
大家如果在项目中使用了npm去下载包的话，项目中一定会有一个npm的管理文件package.json。
打开package.json,你会看到类似如下所示的内容
{ "name": "todolist", "version": "1.0.0", "description": "todolist", "author": "chirs xiong", "private": true, "scripts": { "predev":"echo $npm_package_name", "dev": "node build/dev-server.js", "start": "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": { "animate.css": "^3.5.2", "element-ui": "^1.3.6", "font-awesome": "^4.7.0", "font-awesome-webpack": "0.0.5-beta.2", "iconate": "^0.2.7", "less": "^2.7.2", "less-loader": "^4.0.4", "particles.js": "^2.0.0", "style-loader": "^0.18.2", "vue": "^2.3.3", "vue-disqus": "^2.0.3", "vue-router": "^2.3.1" }, "devDependencies": { "autoprefixer": "^6.7.2", "babel-core": "^6.22.1", "babel-eslint": "^7.1.1", "babel-loader": "^6.4.1", "babel-plugin-component": "^0.9.1", "babel-plugin-istanbul": "^4.1.1", "babel-plugin-transform-runtime": "^6.22.0", "babel-preset-env": "^1.3.2", "babel-preset-es2015": "^6.24.1", "babel-preset-stage-2": "^6.22.0", "babel-register": "^6.22.0", "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": "^0.28.4", "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": "^0.11.2", "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", "lolex": "^1.5.2", "mocha": "^3.2.0", "nightwatch": "^0.9.12", "node-sass": "^4.5.3", "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", "sass-loader": "^6.0.6", "selenium-server": "^3.0.1", "semver": "^5.3.0", "shelljs": "^0.7.6", "sinon": "^2.1.0", "sinon-chai": "^2.8.0", "transform-loader": "^0.2.4", "url-loader": "^0.5.8", "vue-loader": "^12.1.0", "vue-style-loader": "^3.0.1", "vue-template-compiler": "^2.3.3", "webpack": "^2.6.1", "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" ]}1.2 scripts脚本
你可以在package.json中看到你项目的基本信息，如名称，项目版本，依赖组件等等。现在大家来看看scripts属性，有没有觉得非常熟悉，我们平时用的dev,start,bulid等都出现在了scripts属性中，而script属性就是npm的脚本。你可以在这里自定义脚本。如下
scripts: { "mock": "node mock/mock-server.js"}像这样定义脚本之后，只要你输入在shell中输入npm run mock 就相当于执行了mock-server.js这个命令
二 总结
其实npm脚本的运行机理就是当你运行npm run时，实际上是默认打开了一个shell窗口，然后输入script中定义的命令。如 npm run mock。其实际上是默认打开了一个shell窗口（当然你看不到）,然后在该窗口中输入node mock/mock-server.js,需要注意的一点是npm run默认打开的shell，其路径默认为node_modules的路径，所以如果你想运行node_modules中的内容，路径中不需要加node_modules