原生js添加及获取cookie&获取上一页面url

<script type="text/javascript">
  function toApp(url){//主函数
    var ref = '';
    if(getCookie('pre_url')){
        ref = getCookie('pre_url');
    }else{
        if (document.referrer.length > 0) {
            ref = document.referrer;
            if (ref.length == 0 && opener.location.href.length > 0) {
                ref = opener.location.href;
            }
        }if(ref.indexOf("irootech.com") > 0 && ref.indexOf("sany") > 0){//验证是否是需要的url
            setCookie('pre_url',ref,1);
        }else{
            ref = '';
        }
    }
    window.location.href=ref+'#'+url;// 跳转到指定的url
  }

  function setCookie(cname, cvalue, exdays) {
    var d = new Date();
    d.setTime(d.getTime() + (exdays * 24 * 60 * 60 * 1000));
    var expires = "expires="+d.toUTCString();
    document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
  }

  function getCookie(cname) {
    var name = cname + "=";
    var ca = document.cookie.split(';');
    for(var i = 0; i < ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0) == ' ') {
            c = c.substring(1);
         }
        if (c.indexOf(name)  == 0) {
            return c.substring(name.length, c.length);
         }
    }
    return "";
  }
</script>