Low Pass Filter

lpf.js

// array of values
var values = [10,8,12,10,11,9,10,12,8,50,10,12,8];

// smoothing whole array
function lpf(values, smoothing){
    var value = values[0];
    for (var i = 1; i < values.length; i++){
        var currentValue = values[i];
        value += (currentValue - value) / smoothing;
        values[i] = Math.round(value);
    }
}

// buffer
var values = [10,8,12,10,11,9,10,12,8,50,10,12,8];

// smoothing value using buffer
function lpfBuffer(nextValue, smoothing) {
    // push new value to the end, and remove oldest one
    var initial = values.shift();
    values.push(nextValue);
    // smooth value using all values from buffer
    return values.reduce(function(last, current) {
        return smoothing * current + (1 - smoothing) * last;
    }, initial);
}