Find first index of a string after index
This code might be helpful
var string = "www.google.com.sdg.jfh.sd",
preString = "sdg",
searchString = ".s",
preIndex = string.indexOf(preString),
searchIndex = preIndex + string.substring(preIndex).indexOf(searchString);
You can test it HERE
var str = "www.google.com.sdg.jfh.sd";
var search = "sdg";
var start_index = str.substring(str.indexOf(search) + search.length).indexOf(".s");
There's a second parameter which controls the starting position of search:
String.prototype.indexOf(arg, startPosition);
So you can do
str.indexOf('s', start_index);