1. A first apparatus comprising: means for, in a case where a second apparatus has generated a first HTTP GET request for a first URL, receiving, via a network connection, data from a HTTP response, the HTTP response having been generated by a web server in response to a HTTP request for the first URL; and modifying means for obtaining, from Javascript in the data, modified Javascript, wherein at least one of the following conditions is satisfied: (a) said modifying means comprises means for, when the Javascript in the data, upon execution, uses a first random number algorithm in an instance, obtaining, as the modified Javascript, Javascript that when executed instead uses in that instance a second algorithm different from the first random number algorithm; (b) said modifying means comprises means for, when the Javascript in the data uses a first chronological algorithm in an instance, obtaining, as the modified Javascript, Javascript that when executed instead uses in that instance a third algorithm different from the first chronological algorithm; and (c) said modifying means comprises means for, when the Javascript in the data, upon execution, uses an algorithm to generate a URL in an instance, obtaining, as the modified Javascript, Javascript that when executed instead uses in that instance a different algorithm to generate a URL, wherein a memory and a processor are included in the first apparatus.