Time increase when offline SetInterval jquery -

i have scenario according when user user online @ every 3 or 4 sec request sent server, problem start when user go offline scenario want increase time of setinterval method of jquery have written code it, no success yet:-

my code this

var interval= function(){       if(hasinternets()){           var inter= 15000;           return inter;       }       else           {           var inter= 15000;           inter+= 15000;           return inter;           }   };   setinterval( function(){         if (hasinternets()) { // here doing             }    }, interval()); 

hasinternet method check internet connection.

so if guys can me, in advance.

since function in javascript objects, can assign inter field object stored between function calls:

var interval = function(inter) {         if (!interval.inter) {             interval.inter = 15000;         }         if (hasinternets()) {             return interval.inter;         } else {             interval.inter += 15000;             return interval.inter;         }     }; setinterval(function() {     if (hasinternets()) {         // here doing     } }, interval());