发现一个很好用的工具, 写了一个公司内部的加载器工具，其他人发现用不了；原来在 package.json 中的 scripts 中设置了 NODE_ENV=production，在 windows 下不能这样设置环境变量的，cross-env 就是屏蔽了在不同平台上这种问题的差异；附一个 css-loader 的 package.json 文件，css-loader 中就用了 cross-env 这个工具：
{
"name": "css-loader",
"version": "3.2.1",
"description": "css loader module for webpack",
"license": "MIT",
"repository": "webpack-contrib/css-loader",
"author": "Tobias Koppers @sokra",
"homepage": "https://github.com/webpack-contrib/css-loader",
"bugs": "https://github.com/webpack-contrib/css-loader/issues",
"main": "dist/cjs.js",
"engines": {"node": ">= 8.9.0"},
"scripts": {
"start": "npm run build -- -w",
"prebuild": "npm run clean",
"build": "cross-env NODE_ENV=production babel src -d dist --ignore \"src/**/*.test.js\"--copy-files",
"validate:runtime": "es-check es5 \"dist/runtime/**/*.js\"","postbuild":"npm run validate:runtime","clean":"del-cli dist","commitlint":"commitlint --from=master","lint:prettier":"prettier \"{**/*,*}.{js,json,md,yml,css}\" --list-different","lint:js":"eslint --cache src test","lint":"npm-run-all -l -p \"lint:**\"",
"prepare": "npm run build",
"release": "standard-version",
"security": "npm audit",
"test:only": "cross-env NODE_ENV=test jest",
"test:watch": "cross-env NODE_ENV=test jest --watch",
"test:coverage": "cross-env NODE_ENV=test jest --collectCoverageFrom=\"src/**/*.js\"--coverage",
"pretest": "npm run lint",
"test": "cross-env NODE_ENV=test npm run test:coverage",
"defaults": "webpack-defaults"
},
"files": [
"dist/",
"lib/",
"index.js"
],
"peerDependencies": {"webpack": "^4.0.0"},
"dependencies": {
"camelcase": "^5.3.1",
"cssesc": "^3.0.0",
"icss-utils": "^4.1.1",
"loader-utils": "^1.2.3",
"normalize-path": "^3.0.0",
"postcss": "^7.0.17",
"postcss-modules-extract-imports": "^2.0.0",
"postcss-modules-local-by-default": "^3.0.2",
"postcss-modules-scope": "^2.1.0",
"postcss-modules-values": "^3.0.0",
"postcss-value-parser": "^4.0.0",
"schema-utils": "^2.0.0"
},
"devDependencies": {
"@babel/cli": "^7.5.0",
"@babel/core": "^7.5.4",
"@babel/preset-env": "^7.5.4",
"@commitlint/cli": "^8.1.0",
"@commitlint/config-conventional": "^8.1.0",
"@webpack-contrib/defaults": "^5.0.2",
"@webpack-contrib/eslint-config-webpack": "^3.0.0",
"babel-jest": "^24.8.0",
"commitlint-azure-pipelines-cli": "^1.0.2",
"cross-env": "^5.2.0",
"del": "^5.0.0",
"del-cli": "^2.0.0",
"es-check": "^5.0.0",
"eslint": "^6.1.0",
"eslint-config-prettier": "^6.0.0",
"eslint-plugin-import": "^2.18.0",
"file-loader": "^4.0.0",
"husky": "^3.0.0",
"jest": "^24.8.0",
"jest-junit": "^7.0.0",
"lint-staged": "^9.2.0",
"memory-fs": "^0.4.1",
"npm-run-all": "^4.1.5",
"postcss-loader": "^3.0.0",
"postcss-preset-env": "^6.7.0",
"prettier": "^1.18.2",
"sass": "^1.22.5",
"sass-loader": "^7.1.0",
"standard-version": "^7.0.0",
"strip-ansi": "^5.2.0",
"webpack": "^4.35.0"
},
"keywords": [
"webpack",
"css",
"loader",
"url",
"import"
]
} 可以看到命令：”cross-env NODE_ENV=production babel src -d dist –ignore ‘src/*/.test.js’ –copy-files”
我们知道 npm scripts 其实是创建了一个 shell，在这个 shell 中设置了环境变量 NODE_ENV, 那么在 nodejs 程序中，process.env.NODE_ENV == “production”, 这个工具的好处解决了跨平台的问题，详细使用参考 https://www.npmjs.com/package/cross-env