html-parser.js

'use strict';

const URL = require('url').URL; // for backwards compability (node < 10)
const cheerio = require('cheerio');

class HTMLParser {

  constructor(html) {
    this.html = html;
    this.$ = cheerio.load(this.html);
  }

  getInlineCSS() {
    let inlineCSS = [];
    this.$('style').each((id, el) => {
      if (typeof el.attribs.src === 'undefined') {
        el.children.forEach(child => {
          inlineCSS.push(child.data);
        });
      }
    });
    return inlineCSS;
  }

  getInlineJS() {
    let inlineJS = [];
    this.$('script').each((id, el) => {
      if (typeof el.attribs.src === 'undefined') {
        el.children.forEach(child => {
          inlineJS.push(child.data);
        });
      }
    });
    return inlineJS;
  }

  getStylesheetURLs(url) {
    const Url = new URL(url);
    let stylesheets = [];

    this.$('link').each((id, el) => {
      if (el.attribs.rel === 'stylesheet' && typeof el.attribs.href !== 'undefined') {
        let style = {};
        let res = el.attribs.href;
        if (res.match(/https?:\/\//) === null) { // protocol is not available
          if (!res.startsWith('//')) { // relative
            res = Url.protocol + '//' + Url.host + ((!res.startsWith('/')) ? '/' : '') + res;
          } else res = Url.protocol + res; // without protocol, but still not relative
        }
        style.url = new URL(res);
        stylesheets.push(style);
      }
    });
    return stylesheets;
  }

  getJavascriptURLs(url) {
    const Url = new URL(url);
    let javascripts = [];

    this.$('script').each((id, el) => {
      if (typeof el.attribs.src !== 'undefined') {
        let js = {};
        let res = el.attribs.src;
        if (res.match(/https?:\/\//) === null) { // protocol is not available
          if (!res.startsWith('//')) { // relative
            res = Url.protocol + '//' + Url.host + ((!res.startsWith('/')) ? '/' : '') + res;
          } else res = Url.protocol + res; // without protocol, but still not relative
        }
        js.url = new URL(res);
        javascripts.push(js);
      }
    });
    return javascripts;
  }

  getImageURLs(url) {
    const Url = new URL(url);
    let images = [];
    this.$('img').each((id, el) => {
      if (typeof el.attribs.src !== 'undefined') {
        let img = {};
        let res = el.attribs.src;
        if (res.match(/https?:\/\//) === null) {
          res = (!res.startsWith('//')) ? res = Url.protocol + '//' + Url.host + ((!res.startsWith('/')) ? '/' : '') + res : Url.protocol + res;
        }
        img.url = new URL(res);
        images.push(img);
      }
    });
    return images;
  }

  getiFrames() {
    let iframes = [];
    this.$('iframe').each((id, el) => {
      if (typeof el.attribs.src !== 'undefined') iframes.push(el.attribs.src);
    });
    return iframes;
  }

  getMetaData() {
    let metatags = {};
    this.$('meta').each((id, el) => {
      const key = Object.keys(el.attribs).find((attr) => ['name', 'property', 'itemprop', 'http-equiv'].indexOf(attr) !== -1);
      const name = el.attribs[key];
      const value = el.attribs['content'];
      if (!metatags[name]) {
        metatags[name] = [];
      }
      metatags[name].push(value);
    });
    return metatags;
  }

  checkPrefetching() {
    let prefetching = [];
    this.$('link').each((id, el) => {
      if (el.attribs.rel === 'dns-prefetch') prefetching.push(el.attribs.href);
    });
    return prefetching;
  }

}

module.exports = HTMLParser;