stats1.js

let data = [1,1,3,5,5];  // This is our array of numbers

// The mean is the sum of the elements divided by the number of elements
let total = 0;
for(let i = 0; i < data.length; i++) total += data[i];
let mean = total/data.length;  // mean == 3; The mean of our data is 3

// To compute the standard deviation, we first sum the squares of
// the deviation of each element from the mean.
total = 0;
for(let i = 0; i < data.length; i++) {
    let deviation = data[i] - mean;
    total += deviation * deviation;
}
let stddev = Math.sqrt(total/(data.length-1));  // stddev == 2