What is the regular expression that matches basically all browser useragent and the main search engine spider?

Implementing the UA Whitelist with PHP requires the ability to match basically all browsers and the main search engine spider UA Regular.
Maybe this is a complicated question, and I'll see if anyone can solve it.

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Implementing the UA Whitelist with PHP requires the ability to match basically all browsers and the main search engine spider UA Regular.
Maybe this is a complicated question, and I'll see if anyone can solve it.

var userAgent = navigator.userAgent.toLowerCase();// Figure out what browser is being usedjQuery.browser = {    version: (userAgent.match( /.+(?:rv|it|ra|ie)[/: ]([d.]+)/ ) || [])[1],    safari: /webkit/.test( userAgent ),    opera: /opera/.test( userAgent ),    msie: /msie/.test( userAgent ) && !/opera/.test( userAgent ),    mozilla: /mozilla/.test(userAgent)&&!/(compatible|webkit)/.test(userAgent)};

For your reference, http://www.bkjia.com/jQuery/449138.html.
Improve the other two clue ideas,
1. In the earliest implementation of jquery, the detection of UA seems to be the use of regular expression detection, and later the compatibility code is "testing" the way;
2. JavaScript advanced programming, the impression is that there is such a code, the third version of the sample code on 233 pages

Add:
This site can be found in the vast majority of browsers and search engine spider ua:http://www.useragentstring.com/pages/useragentstring.php
UA description for IE: https://msdn.microsoft.com/en-us/library/ms537503 (v=vs.85). aspx
The UA description for Firefox: https://developer.mozilla.org/en-US/docs/Browser_detection_using_the_user_agent
UA Note for Chrome: https://developer.chrome.com/multidevice/user-agent

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