get-css/index.js

Get CSS from a URL

var q = require('q')
var isCss = require('is-css')
var isPresent = require('is-present')
var isBlank = require('is-blank')
var isUrl = require('is-url-superb')
var fetch = require('node-fetch')
var AbortController = require('abort-controller')
var cheerio = require('cheerio')
var normalizeUrl = require('normalize-url')
var stripHtmlComments = require('strip-html-comments')
var stripWaybackToolbar = require('strip-wayback-toolbar')
var resolveCssImportUrls = require('resolve-css-import-urls')
var ua = require('ua-string')

var getLinkContents = require('./utils/get-link-contents')
var createLink = require('./utils/create-link')

module.exports = function (url, options, html) {
  var deferred = q.defer()
  options = options || {}
  options.timeout = options.timeout || 5000

  if (typeof url !== 'string' || isBlank(url) || !isUrl(url)) {
    throw new TypeError('get-css expected a url as a string')
  }

  url = normalizeUrl(url, { stripWWW: false })

  if (options.ignoreCerts) {
    process.env.NODE_TLS_REJECT_UNAUTHORIZED = '0'
  }

  var status = {
    parsed: 0,
    total: 0,
  }

  var result = {
    links: [],
    styles: [],
    css: '',
  }

  function handleResolve() {
    if (status.parsed >= status.total) {
      deferred.resolve(result)
    }
  }

  function parseHtml(html) {
    var stripWayback = options.stripWayback || false
    if (stripWayback) {
      html = stripWaybackToolbar(html)
    }
    var $ = cheerio.load(html)
    result.pageTitle = $('head > title').text()
    result.html = html

    $('[rel=stylesheet]').each(function () {
      var link = $(this).attr('href')
      if (isPresent(link)) {
        result.links.push(createLink(link, url))
      } else {
        result.styles.push(stripHtmlComments($(this).html()))
      }
    })

    $('style').each(function () {
      result.styles.push(stripHtmlComments($(this).html()))
    })

    status.total = result.links.length + result.styles.length
    if (!status.total) {
      handleResolve()
    }

    result.links.forEach(function (link) {
      getLinkContents(link.url, options)
        .then(function (css) {
          handleCssFromLink(link, css)
        })
        .catch(function (error) {
          link.error = error
          status.parsed++
          handleResolve()
        })
    })

    result.styles.forEach(function (css) {
      result.css += css
      status.parsed++
      handleResolve()
    })
  }

  function handleCssFromLink(link, css) {
    link.css += css

    parseCssForImports(link, css)

    status.parsed++
    handleResolve()
  }

  // Handle potential @import url(foo.css) statements in the CSS.
  function parseCssForImports(link, css) {
    link.imports = resolveCssImportUrls(link.url, css)
    status.total += link.imports.length
    result.css += css

    link.imports.forEach(function (importUrl) {
      var importLink = createLink(importUrl, importUrl)
      result.links.push(importLink)

      getLinkContents(importLink.url, options)
        .then(function (css) {
          handleCssFromLink(importLink, css)
        })
        .catch(function (error) {
          link.error = error
          status.parsed++
          handleResolve()
        })
    })
  }

  function handleBody(body) {
    if (isCss(url)) {
      var link = createLink(url, url)
      result.links.push(link)
      handleCssFromLink(link, body)
    } else {
      parseHtml(body)
    }
  }

  if (html) {
    handleBody(html)
  } else {
    var controller = new AbortController()

    var options = Object.assign({}, options)
    options.headers = options.headers || {}
    options.headers['User-Agent'] = options.headers['User-Agent'] || ua
    options.signal = controller.signal

    var timeoutTimer = setTimeout(() => {
      controller.abort()
    }, options.timeout)
    fetch(url, options)
      .then((response) => {
        if (response && response.status != 200) {
          if (options.verbose) {
            console.log('Received a ' + response.status + ' from: ' + url)
          }
          deferred.reject({ url: url, status: response.status })
          return
        }

        return response.text()
      })
      .then((body) => {
        handleBody(body)
      })
      .catch((error) => {
        if (options.verbose) {
          console.log('Error from ' + url + ' ' + error)
        }
        deferred.reject(error)
      })
      .finally(() => {
        clearTimeout(timeoutTimer)
      })
  }

  return deferred.promise
}