1. A computer usable program product comprising a computer readable storage medium including computer usable code for browser cache cleanup, the computer usable code comprising: computer usable code for computing, using a processor and a memory of a device, to consider for eviction a data item stored in a cache of a browser application, a probability that the data item will be needed again during a period after the eviction; computer usable code for determining a type of a data network that will be available at the device during the period; computer usable code for computing, a cost of obtaining the data item over a data network of the type of the data network, from a location of the device during the period; computer usable code for computing, using the probability that the data item will be needed again during the period, and further using the cost of obtaining the data item over the data network, a weight of the data item; computer usable code for associating the weight with the data item as a part of associating a set of weights with a set of data items in the cache; and computer usable code for selecting for eviction from the cache the data item because the weight is a lowest weight in the set of weights.