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.

I have found an example of how to to detect a certain browser, but am unable to find examples of how to detect a search crawler:

/MSIE (\d+\.\d+);/.test(navigator.userAgent); //test for MSIE x.x

Example of search crawlers I want to block:

Google 
Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html) 
Googlebot/2.1 (+http://www.googlebot.com/bot.html) 
Googlebot/2.1 (+http://www.google.com/bot.html) 

Baidu 
Baiduspider+(+http://www.baidu.com/search/spider_jp.html) 
Baiduspider+(+http://www.baidu.com/search/spider.htm) 
BaiDuSpider 

Answer 1

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: ...
}