highcharts random trend

HTML

<script src="http://code.highcharts.com/highcharts.js"></script>
<script src="http://code.highcharts.com/modules/exporting.js"></script>

<div id="container" style="min-width: 400px; height: 400px; margin: 0 auto"></div>

JavaScript

function getTrend(maxRange){
    var range = Math.floor(Math.random()*maxRange);
    var plusRange = Math.floor(Math.random()*range);
    console.log(["maxRange", maxRange, "range", range, "plusRange", plusRange]);
    return {rangeTotal: range, plusRange: plusRange, minusRange: (range-plusRange)}
}

function getNumberWithTrend( trend ) {
    var randomNumber = Math.floor(Math.random()*trend.rangeTotal);
    if  (randomNumber <= trend.plusRange) { //if in plus range, return as it is
        return randomNumber * -1;
    } else { // if in minus range, deduct plus range and multiply -1
        return ( randomNumber - trend.plusRange );
    }
}
            
function getTrendedData( startNumber, percentage) {
    var trend = getTrend( 1000000/100.0 * percentage);
    //console.log(trend);
        
    var data = [startNumber];
    for (var i=0; i< 100; i++) {
        startNumber -= getNumberWithTrend(trend);
        data.push( {x:i, y:startNumber} )
    }

    return data;
}
var chart;
var dailyVariationPct = 20;
$( function() {
    chart = new Highcharts.Chart({
        chart: {
            renderTo: 'container',
            type: 'scatter'
        },
        series: [{
            name: 'Trend',
            data: getTrendedData(1000000,dailyVariationPct ) //startNumber, variation%
        }]
    });
});