求助：怎么样替换最后一个","逗号啊

Question

<script language=javascript>str="88,21,1,2,3,1,"str=str.replace(/,+$/,"");
</script>

Answer 1

str = str.substr(0, str.length-1)

Answer 2

str="88,21,1,2,3,1,"
var sss = str.substr(0, str.lastIndexOf(","))+ str.substr(str.lastIndexOf(",")+1, str.length-1)
alert(sss);

Answer 3

<script language=javascript>str="88,21,1,2,3,1,";
if(str.substring(str.length-1,str.length)=="'") str=str.substr(0, str.length-1);</script>

Answer 4

上面错了
<script language=javascript>str="88,21,1,2,3,1,";
if(str.substring(str.length-1,str.length)==",") str=str.substr(0, str.length-1);</script>