jquery判断浏览器

var userAgent = navigator.userAgent.toLowerCase();

// Figure out what browser is being used
jQuery.browser = {
version: (userAgent.match( /.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/ ) || [0,'0'])[1],
safari: /webkit/.test( userAgent ),
opera: /opera/.test( userAgent ),
msie: /msie/.test( userAgent ) && !/opera/.test( userAgent ),
mozilla: /mozilla/.test( userAgent ) && !/(compatible|webkit)/.test( userAgent )
};  

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if ($.browser.msie && ($.browser.version == "6.0") && !$.support.style) { alert("6"); }