Laravel Mix：更新 Node.js 依赖项

I am trying to compile webpack configuration files with Laravel Mix.

Following webpack episode on Laracasts Vue 2 series,

// Scripts

  "scripts": {
    "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"
  },
....

// mix
mix.js('resources/assets/js/app.js', 'public/js')
.sass('resources/assets/sass/app.scss', 'public/css')
.version();

When I run $ npm run dev, I get an error:

npm ERR! Exit status 1

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'.

// Running

npm ERR! node v4.4.5
npm ERR! npm v2.15.5

// The error points to
let extractPlugin = new plugins.ExtractTextPlugin(
/Users/User/Code/project/node_modules/laravel-mix/setup/webpack.config.js:126

The issue seems to be update a Node.js dependency: https://github.com/JeffreyWay/laravel-mix/issues/264

How do I update the Node.js dependency?

I am trying:

$ brew upgrade node : Error = node not installed
$ node -v = 2.15.5
$ npm -v = 4.4.5
$ brew install node // installs but throws error

Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
Could not symlink bin/node
Target /usr/local/bin/node
already exists. You may want to remove it:
  rm '/usr/local/bin/node'

To force the link and overwrite all conflicting files:
  brew link --overwrite node

要列出将被删除的所有文件，请执行以下操作:
  brew link --overwrite --dry-run node

Possible conflicting files are:
/usr/local/bin/node
...

**$ brew upgrade node // says node 7.5.0 already installed**
$ npm run dev // same error
$ node -v = 4.4.5

我还运行了已安装的$BREW安装 node ，但收到错误:

Error: The brew link step did not complete successfully.
The formula built, but is not symlinked into /usr/local.
Could not symlink bin/node.
Target /usr/local/bin/node
already exists. You may want to remove it:
rm '/usr/local/bin/node'

To force the link and overwrite all conflicting files:

brew link --overwrite node

要列出将被删除的所有文件，请执行以下操作:

brew link --overwrite --dry-run node