With a quick google on Javascript If statments I beleive I have got there - thanks Bjorn :0) Your answer led me to get there !!!
// push data points
$(series).find('data point').each(function(i, point) {
var floatVal = parseFloat($(point).text());
if (!isNaN(floatVal)) {
seriesOptions.data.push(floatVal);
}
else {
seriesOptions.data.push(null);
}
console.log(floatVal)
});