xml文件问题

Question

<req><chatRoom><id>wwww</id><cname>ddddd</cname><ctype>1</ctype><maxUsers>500</maxUsers><welcomes>ssss</welcomes><description>qqqq</description><status>1</status><startTime>tttt</startTime><closeTime>rrrrrr</closeTime><createTime>Thu Oct 11 14:19:47 UTC+0800 2012</createTime></chatRoom></req>我想在req后面加上一些参数，这个怎么弄，请教高手<req id="sample"><chatRoom><id>wwww</id><cname>ddddd</cname><ctype>1</ctype><maxUsers>500</maxUsers><welcomes>ssss</welcomes><description>qqqq</description><status>1</status><startTime>tttt</startTime><closeTime>rrrrrr</closeTime><createTime>Thu Oct 11 14:19:47 UTC+0800 2012</createTime></chatRoom></req>

Answer 1

想在req后面添加些参数如："id='sample'"

Answer 2

replace(/<req>/g,'<req id="sample">')