Laravel 5.2，为什么安装＆＃39; npm不安装laravel-elixir？

Question

我必须为每个新项目手动运行npm install laravel-elixir。

通过运行composer create-project laravel/laravel

创建的Laravel项目

package.json包含：

{
  "private": true,
  "scripts": {
    "prod": "gulp --production",
    "dev": "gulp watch"
  },
  "devDependencies": {
    "gulp": "^3.9.1",
    "laravel-elixir": "^5.0.0",
    "bootstrap-sass": "^3.0.0"
  }
}