javascript读取cookie

<mce:script language="javascript" type="text/javascript"><!-- function checkCookie() { var cookieStr = document.cookie; username=getCookie("cdb_auth"); if(username==""){ alert("你还没有登录！请登录！"); return false; } return ""; } function getCookie(c_name){ if (document.cookie.length>0){ c_start=document.cookie.indexOf(c_name + "="); if (c_start!=-1){ c_start=c_start + c_name.length+1+1 ; //如果是字符串要去掉冒号 c_end=document.cookie.indexOf(";",c_start); if (c_end==-1) { c_end=document.cookie.length } return unescape(document.cookie.substring(c_start,c_end-1)); } } return "" } // --></mce:script>