Detect Search Crawlers via JavaScript

Question

I am wondering how would I go abouts in detecting search crawlers? The reason I ask is because I want to suppress certain JavaScript calls if the user agent is a bot.

<

Answer 1

Try this. It's based on the crawlers list on available on https://github.com/monperrus/crawler-user-agents

var botPattern = "(googlebot\/|bot|Googlebot-Mobile|Googlebot-Image|Google favicon|Mediapartners-Google|bingbot|slurp|java|wget|curl|Commons-HttpClient|Python-urllib|libwww|httpunit|nutch|phpcrawl|msnbot|jyxobot|FAST-WebCrawler|FAST Enterprise Crawler|biglotron|teoma|convera|seekbot|gigablast|exabot|ngbot|ia_archiver|GingerCrawler|webmon |httrack|webcrawler|grub.org|UsineNouvelleCrawler|antibot|netresearchserver|speedy|fluffy|bibnum.bnf|findlink|msrbot|panscient|yacybot|AISearchBot|IOI|ips-agent|tagoobot|MJ12bot|dotbot|woriobot|yanga|buzzbot|mlbot|yandexbot|purebot|Linguee Bot|Voyager|CyberPatrol|voilabot|baiduspider|citeseerxbot|spbot|twengabot|postrank|turnitinbot|scribdbot|page2rss|sitebot|linkdex|Adidxbot|blekkobot|ezooms|dotbot|Mail.RU_Bot|discobot|heritrix|findthatfile|europarchive.org|NerdByNature.Bot|sistrix crawler|ahrefsbot|Aboundex|domaincrawler|wbsearchbot|summify|ccbot|edisterbot|seznambot|ec2linkfinder|gslfbot|aihitbot|intelium_bot|facebookexternalhit|yeti|RetrevoPageAnalyzer|lb-spider|sogou|lssbot|careerbot|wotbox|wocbot|ichiro|DuckDuckBot|lssrocketcrawler|drupact|webcompanycrawler|acoonbot|openindexspider|gnam gnam spider|web-archive-net.com.bot|backlinkcrawler|coccoc|integromedb|content crawler spider|toplistbot|seokicks-robot|it2media-domain-crawler|ip-web-crawler.com|siteexplorer.info|elisabot|proximic|changedetection|blexbot|arabot|WeSEE:Search|niki-bot|CrystalSemanticsBot|rogerbot|360Spider|psbot|InterfaxScanBot|Lipperhey SEO Service|CC Metadata Scaper|g00g1e.net|GrapeshotCrawler|urlappendbot|brainobot|fr-crawler|binlar|SimpleCrawler|Livelapbot|Twitterbot|cXensebot|smtbot|bnf.fr_bot|A6-Indexer|ADmantX|Facebot|Twitterbot|OrangeBot|memorybot|AdvBot|MegaIndex|SemanticScholarBot|ltx71|nerdybot|xovibot|BUbiNG|Qwantify|archive.org_bot|Applebot|TweetmemeBot|crawler4j|findxbot|SemrushBot|yoozBot|lipperhey|y!j-asr|Domain Re-Animator Bot|AddThis)";
var re = new RegExp(botPattern, 'i');
var userAgent = navigator.userAgent; 
if (re.test(userAgent)) {
    console.log('the user agent is a crawler!');
}

Answer 2

The following regex will match the biggest search engines according to this post.

/bot|google|baidu|bing|msn|teoma|slurp|yandex/i
    .test(navigator.userAgent)

The matches search engines are:

• Baidu
• Bingbot/MSN
• DuckDuckGo (duckduckbot)
• Google
• Teoma
• Yahoo!
• Yandex

Additionally, I've added bot as a catchall for smaller crawlers/bots.

Answer 3

The "test for MSIE x.x" example is just code for testing the userAgent against a Regular Expression. In your example the Regexp is the

/MSIE (\d+\.\d+);/

part. Just replace it with your own Regexp you want to test the user agent against. It would be something like

/Google|Baidu|Baiduspider/.test(navigator.userAgent)

where the vertical bar is the "or" operator to match the user agent against all of your mentioned robots. For more information about Regular Expression you can refer to this site since javascript uses perl-style RegExp.

Answer 4

isTrusted property could help you.

The isTrusted read-only property of the Event interface is a Boolean that is true when the event was generated by a user action, and false when the event was created or modified by a script or dispatched via EventTarget.dispatchEvent().

eg:

isCrawler() {
  return event.isTrusted;
}

⚠ Note that IE isn't compatible.

Read more from doc: https://developer.mozilla.org/en-US/docs/Web/API/Event/isTrusted

Answer 5

This is the regex the ruby UA agent_orange library uses to test if a userAgent looks to be a bot. You can narrow it down for specific bots by referencing the bot userAgent list here:

/bot|crawler|spider|crawling/i

For example you have some object, util.browser, you can store what type of device a user is on:

util.browser = {
   bot: /bot|googlebot|crawler|spider|robot|crawling/i.test(navigator.userAgent),
   mobile: ...,
   desktop: ...
}