code: function getLinkDensity (node, $) {
    const links = node.find('a')
    const textLength = node.text().length
    let linkLength = 0
  
    links.each(function (index, elem) {
      const href = $(this).attr('href')
      if (!href || (href.length > 0 && href[0] === '#')) {
        return
      }
      linkLength += $(this).text().length
    })
  
    return linkLength / textLength || 0
  }
docs: Get Link density of this node.
  Total length of link text in this node divided by the total text of the node.
  Relative links are not included.