Flawed HTML Parser

HTMLFragment.js

(function(input) {

  class HTMLFragment {
    constructor(htmlText) {
      this.raw = htmlText
      this.parsed = HTMLFragment.parse(removeWhitespace(htmlText))
      return this
    }
  
    static parse(htmlText) {
      var elementPattern = /<(\w+)(.[^>]+)?>(.+)<\/\1>/
      var attributesPattern = /(?:\w(?:-\w+)?)+(?:=(?:"|').[^"']+(?:"|'))?/g
      var match = htmlText.match(elementPattern)
      if (!match) {
        return null
      }

      var [, tagName, attributesText, innerHTML ] = match

      var firstChild = HTMLFragment.parse(innerHTML)

      var attributes = attributesText
        .trim()
        .match(attributesPattern)
        .map(attr => {
          var [ key, value ] = attr.split('=')
          return [ key, (value || '').slice(1, -1) ]
        })
        .reduce((prev, curr) => (prev[curr[0]] = curr[1] || true, prev), {})

      return {
        tagName,
        attributes,
        innerHTML,
        firstChild
      }
    }
  }

  function removeWhitespace(html) {
    return html.replace(/\n/g, '').replace(/>\s+/g, '>').trim()
  }
  
  return new HTMLFragment(input)

})(`
  <div class="container pull-left" id="hello">
    <h1 id="main-header" class="title" aria-role="title">Oh my header!</h1>
    <p>
      Lorem ipsum dolor sit amet <a href="http://enes.in">Enes</a>. So, good bye!
    </p>
  </div>
`)