So I have this code that I found here at Stack Exchange that lets me highlight rows based on date:

SP.SOD.executeFunc("clienttemplates.js", "SPClientTemplates", function() { 

SPClientTemplates.TemplateManager.RegisterTemplateOverrides({
OnPostRender: function (ctx) {

    // get today's date
    var today = new Date();
    // zero out the time portion so we will only compare days
    today.setHours(0,0,0,0);
    var tenDaysAgo=new Date(-864000000);
    tenDaysAgo.setHours(0,0,0,0);

    var rows = ctx.ListData.Row;
    for (var i = 0; i < rows.length; i++) {

        // get the date set in your date YourDateField
        var itemDate = new Date(rows[i]['Due_x0020_Date']);
        // zero out the time portion so we only compare days
        itemDate.setHours(0,0,0,0);

        var rowId = GenerateIIDForListItem(ctx, rows[i]);
        var row = document.getElementById(rowId);

        if (itemDate <= today) {
            row.style.backgroundColor = '#ED9898';
        }
        if (itemDate >= tenDaysAgo && itemDate >today ) {
            row.style.backgroundColor = 'yellow';
        }
    }
}

}); });

The problem I am having is in this line, where I want to check if the due date is within ten days of today.

    if (itemDate >= tenDaysAgo && itemDate >today ) {
            row.style.backgroundColor = 'yellow';
        }

Everything is working except this line, which basically looks at the due date and if it is less than today, it highlights it in yellow. I am at wits end trying to figure this out. I really hope someone here can help with this. I am using a script editor below the list, if that matters. I am very new to javascript. We are using sharepoint online, but I can't use JSON because we are using the classic view on this site.