Hash fragments in the URL can be used to bookmark a particular view of an interactive visualization so that it can be shared. This is super useful, and enabling it is a reward for effectively managing the state of the visualization in your code.
For example, consider the URL: http://weather.zanarmstrong.com/#city=FARGO&metric=cloudCover&colored=1
To access the hash, assuming it’s seperated by &:
Then parse the resulting array in order to set the state of the visualization to the one specified in the URL.
To set a hash, write something like:
window.location.hash = "city=FARGO&metric=cloudCover&colored=1";
Clearly you can paste together text and variables to set this, based on whatever your current state is.