Question

Given:

var
isIE = $.browser.msie && !$.support.opacity, 
isIE6 = isIE && $.browser.version < 7;

Which would be faster:

if(isIE6){ doSomething(); }
else { doSomethingElse(); }

OR

if(!isIE6){ doSomethingElse(); }
else { doSomething(); }

Are they exactly the same in terms of speed?

Answer 1

Given this test on a 1,000,000 iteration loop, no difference.

var test = true;

var count = 1000000;
var stop, start = new Date();

while(count--) {
    if(test) ; // Change to !test
    else ;
}

stop = new Date();

alert(stop - start);

Tested in Firefox, Safari & IE8.

Other processes running on the system, performing the test several times in each browser returned the same general variation in milliseconds irrespective of !.