IE和Firefox正则表达式问题

Question

Why the following pattern in IE and Firefox matches result different?

var str = 'a,b,c , d,   e   ,f';
var matches = str.split(/(\s+)?,(\s+)?/);
alert(matches);

IE: 
a,b,c,d,e,f

firefox: 
a,,,b,,,c, , ,d,,   ,e,   ,,f

how to match like IE result? please answer me :(

ie8 and firefox v3.6.8

Answer 1

var str = 'a,b,c , d,   e   ,f';
var matches = str.split(/\s*,\s*/);
alert(matches);

The reason you are getting the extra entries in Firefox is because the parentheses ( () ) in your regular expression are captured as additional matches. This is normally the expected behaviour and I would argue that IE has a bug because it doesn't do it. In my example, there are no parentheses in the regex, so you get only the text between the matches.