# Calculating Percentiles on Streaming Data Part 4: JavaScript Library

This is part 4 of my series on calculating percentiles on streaming data.

I have created a reusable JavaScript library which contains my implementation of the streaming percentile algorithms found within this blog post and published it to GitHub and NPM. Here’s what using it looks like:

```
var sp = require("streaming-percentiles');
// epsilon is allowable error. As epsilon becomes smaller, the
// accuracy of the approximations improves, but the class consumes
// more memory.
var epsilon = 0.1;
var gk = new sp.GK(epsilon);
for (var i = 0; i < 1000; ++i)
gk.insert(Math.random());
var p50 = gk.quantile(0.5); // Approx. median
var p95 = gk.quantile(0.95); // Approx. 95th percentile
```

You can find it here: