求个正则表达式

Question

<SCRIPT LANGUAGE="JavaScript">
<!--
var a = '11,22,,33,44,,,55,';var b = a.replace(/(\d+),*/g,"$1" + ",");alert(b)//-->
</SCRIPT>

Answer 1

<SCRIPT LANGUAGE="JavaScript">
<!--
var a = '11,22,,33,44,,,55';var b = a.replace(/(\d+),*/g,function(){return arguments[1] + ',';});alert(b)//-->
</SCRIPT>

Answer 2

不用正则也行
var a = "11,22,,33,44,,,55";
while(a.indexOf(",,") > 0)
{
    a = a.replace(",,", ",");
}
document.write(a);

Answer 3

var a = "11,22,,33,44,,,55,";
a = a.replace(/(^,+)|(,+$)/, "").replace(/,+/g, ",");
alert(a);