# How does medium.com (for example) generate the URL fragment hash

javascripttrackingwebsite

Has anyone identified the scripts or techniques used by medium.com (or other popular site) to generate what appears to be a unique hash value after the URL fragment?

Contrived example: #.lfr25xei4

They change with every page refresh (at least in my experience).

(I considered asking this on Stack Overflow but not sure it belongs there.)

• I know it's been a few months since this question was posted, but I got interested in the same thing and here are my findings.

The hash is generated client-side, in Javascript, and it's based on current timestamp. The code looks like this:

hash = generateHash().substr(0, 9)

generateHash = function() {
return Math.floor(2147483648 * Math.random()).toString(36) +
Math.abs(Math.floor(2147483648 * Math.random()) ^ (0, getTimestamp)()).toString(36)
}

getTimestamp = Date.now || function() {
return +new Date
}


(functions have been renamed for clarity)