node-ztable
A simple module to convert z-scores to percentiles using the standard normal table. If a z-score is higher than 3.49 or lower than -3.49, it will return 1 or 0 respectively. Example usage:
var ztable = require('ztable');
var zscore = -1.3452;
console.log(ztable(zscore));
// => 0.0901