1 function changeURLPar(url, ref, value) { 2     var str = ""; 3     if (url.indexOf(‘?‘) != -1) 4         str = url.substr(url.indexOf(‘?‘) + 1); 5     else 6         return url + "?" + ref + "=" + value; 7     var returnurl = ""; 8     var setparam = ""; 9     var arr;10     var modify = "0";11     if (str.indexOf(‘&‘) != -1) {12         arr = str.split(‘&‘);13         for (i in arr) {14             if (arr[i].split(‘=‘)[0] == ref) {15                 setparam = value;16                 modify = "1";17             }18             else {19                 setparam = arr[i].split(‘=‘)[1];20             }21             returnurl = returnurl + arr[i].split(‘=‘)[0] + "=" + setparam + "&";22         }23         returnurl = returnurl.substr(0, returnurl.length - 1);24         if (modify == "0")25             if (returnurl == str)26                 returnurl = returnurl + "&" + ref + "=" + value;27     }28     else {29         if (str.indexOf(‘=‘) != -1) {30             arr = str.split(‘=‘);31             if (arr[0] == ref) {32                 setparam = value;33                 modify = "1";34             }35             else {36                 setparam = arr[1];37             }38             returnurl = arr[0] + "=" + setparam;39             if (modify == "0")40                 if (returnurl == str)41                     returnurl = returnurl + "&" + ref + "=" + value;42         }43         else44             returnurl = ref + "=" + value;45     }46     return url.substr(0, url.indexOf(‘?‘)) + "?" + returnurl;47 }