jquery在文本框之后添加红*
var addHtml="<span class='text_red'>*</span>";
function req(re){
if(re.parent("td").find("span").length==0){
re.attr("require", "true");
re.parent("td").append(addHtml);
}
};
function notreq(re){
re.attr("require", "false");
re.parent("td").find("span").remove();
};