Function in plugin options is filtered

[dongyuanxin]

• I confirm that this is an issue rather than a question.

Bug report

I'm writing a comment plugin for vuepress. It should listen router change and refresh automaticly.

However, when the user sets the option to a function, the option seems to be filtered and disappear.

Steps to reproduce

① Register local plugin

module.exports = {
  // ...
  plugins: [
    [
      require('./plugins/comment-plugin'),
      {
        name: 'comment',
        options: (frontmatter) => {
          return {...frontmatter}
        }
      }
    ],
  ]
}

② Define global variables

./plugins/comment-plugin/index.js:

const path = require('path')
module.exports = (options, context) => {
  return {
    /***** set global variable options *****/
    define () {
      return {
        options
      }
    },
    /***** end *****/
    enhanceAppFiles: path.resolve(__dirname, 'enhanceAppFile.js'),
    globalUIComponents: 'Comment' 
  }
}

③ Read variable

Comment.vue:

<script>
export default {
  mounted () {
    console.log(options)
  }
}
</script>

What is expected?

The output of Chrome console should be an Object with attributes name[string] and options[function].

What is actually happening?

Only name[string] is output, options[function] disappears.

As shown below:

Other relevant information

• My VuePress version is lower and euqal than 1.0.0-alpha.47:

  • VuePress version:
  • OS:
  • Node.js version:
  • Browser version:
  • Is this a global or local install?
  • Which package manager did you use for the install?
  • Does this issue occur when all plugins are disabled?

• My VuePress version is higher than 1.0.0-alpha.47, the following is the output of npx vuepress info in my VuePress project:

Environment Info:

  System:
    OS: Windows 10
    CPU: (4) x64 Intel(R) Core(TM) i5-4210H CPU @ 2.90GHz
  Binaries:
    Node: 10.15.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.13.0 - C:\Users\godbmw\AppData\Roaming\npm\yarn.CMD
    npm: 6.4.1 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Not Found
  npmPackages:
    @vuepress/core: Not Found
    @vuepress/theme-default: Not Found
    vuepress: Not Found
  npmGlobalPackages:
    vuepress: Not Found