Standard deviation of set of values

standard-deviation.js

/**
 * Returns standard deviation of set of values.
 * 
 * @param   {number[]} values - Array of values.
 * @returns {number}   Standard devation of values.
 */
function stdDeviation(values) {
    const avgOfValues = average(values);
    const squaresOfDiffs = values.map(value => (value-avgOfValues)**2);
    const avgOfSquaresOfDiffs = average(squaresOfDiffs);
    return Math.sqrt(avgOfSquaresOfDiffs);

    function average(values) {
        return values.reduce((sum, value) => sum + value, 0) / values.length;
    }
}