新安装的Laravel，按照官方教程试图安装Mix，使用默认的package.json在项目根目录运行以下命令（package.json是node的依赖文件，就像composer.json是composer的依赖文件是一个道理。
npm install
按照成功，然后运行
// Run all Mix tasks...
npm run dev
// Run all Mix tasks and minify output...
npm run production
报错
> node node_modules/cross-env/bin/cross-env.js NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js
module.js:442
throw err;
^
Error: Cannot find module '/Applications/XAMPP/xamppfiles/htdocs/visitor_backend/node_modules/cross-env/bin/cross-env.js'
at Function.Module._resolveFilename (module.js:440:15)
at Function.Module._load (module.js:388:25)
at Module.runMain (module.js:575:10)
at run (bootstrap_node.js:352:7)
at startup (bootstrap_node.js:144:9)
at bootstrap_node.js:467:3
npm ERR! Darwin 16.0.0
npm ERR! argv "/usr/local/Cellar/node/6.3.1/bin/node" "/usr/local/bin/npm" "run" "dev"
npm ERR! node v6.3.1
npm ERR! npm v3.10.3
npm ERR! code ELIFECYCLE
npm ERR! @ dev: `node node_modules/cross-env/bin/cross-env.js NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the @ dev script 'node node_modules/cross-env/bin/cross-env.js NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! node node_modules/cross-env/bin/cross-env.js NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js
npm ERR! You can get information on how to open an issue for this project with:
npm ERR! npm bugs
npm ERR! Or if that isn't available, you can get their info via:
npm ERR! npm owner ls
npm ERR! There is likely additional logging output above.
npm ERR! Please include the following file with any support request:
npm ERR! /Applications/XAMPP/xamppfiles/htdocs/visitor_backend/npm-debug.log
细看发现是cross-env.js文件找不到了，再看package.json里发现启动参数里写的文件路径和node_modules里面的路径不一样，少了个\dist\文件夹路径，加上后可跑。
