JavaScript browser Verification Code (from discuz)

Check Discuz! When the source code is found, a piece of browser verification code is still classic:
Copy codeThe Code is as follows:
Var BROWSER = {};
Var USERAGENT = navigator. userAgent. toLowerCase ();
Alert (USERAGENT );
BROWSER. ie = window. ActiveXObject & USERAGENT. indexOf ('msi ')! =-1 & USERAGENT. substr (USERAGENT. indexOf ('msi') + 5, 3 );
BROWSER. firefox = document. getBoxObjectFor & USERAGENT. indexOf ('Firefox ')! =-1 & USERAGENT. substr (USERAGENT. indexOf ('Firefox ') + 8, 3 );
BROWSER. chrome = window. MessageEvent &&! Document. getBoxObjectFor & USERAGENT. indexOf ('chrome ')! =-1 & USERAGENT. substr (USERAGENT. indexOf ('chromi') + 7, 10 );
BROWSER. opera = window. opera & opera. version ();
BROWSER. safari = window. openDatabase & USERAGENT. indexOf ('safari ')! =-1 & USERAGENT. substr (USERAGENT. indexOf ('safari ') + 7, 8 );
BROWSER. other =! BROWSER. ie &&! BROWSER. firefox &&! BROWSER. chrome &&! BROWSER. opera &&! BROWSER. safari;
BROWSER. firefox = BROWSER. chrome? 1: BROWSER. firefox;