code: function getContent(filePath) {
    // 判断缓存
    if (wxssCache[filePath]) {
      return wxssCache[filePath]
    }
  
    let wxss = _.readFile(filePath)
  
    if (wxss) {
      const importList = getImportList(wxss, filePath)
  
      importList.forEach(item => {
        wxss = wxss.replace(item.code, getContent(item.path))
      })
    }
  
    // 缓存 wxss
    wxssCache[filePath] = wxss || ''
  
    return wxssCache[filePath]
  }
docs: 获取 wxss 内容