Axis ticks based on range

axis-ticks.js

// based on https://stackoverflow.com/questions/8855026/generate-axis-scale
function calculateTicks(min, max, tickCount) {
    var span = max - min,
        step = Math.pow(10, Math.floor(Math.log(span / tickCount) / Math.LN10)),
        err = tickCount / span * step;
    
    // Filter ticks to get closer to the desired count.
    if (err <= .15) step *= 10;
    else if (err <= .35) step *= 5;
    else if (err <= .75) step *= 2;
    
    // Round start and stop values to step interval.
    var tstart = Math.ceil(min / step) * step,
        tstop = Math.floor(max / step) * step + step * .5,
        ticks = [],
        x;
    
    // now generate ticks
    for (var i=tstart; i < tstop; i += step) {
        ticks.push(Number(i.toFixed(2))); // handle floating point issues  
    }
    ticks.push(Number((i).toFixed(2))); // handle floating point issues  
    return [...new Set(ticks)]; // strip the duplicates
}
console.clear();
console.log(calculateTicks(0, 99.85, 10));
console.log(calculateTicks(0, 17.85, 10));
console.log(calculateTicks(0, 7.85, 10));
console.log(calculateTicks(0, .75, 10));
console.log(calculateTicks(0, .01, 10));