window.onload = function() {
    document.getElementById('chart-nseries').onblur = setSeriesEdits;
}

function setSeriesEdits() {
    var nSeries = document.getElementById('chart-nseries').value;
    var div = document.getElementById('control-data');
    for (var i=0; i<nSeries; i++) {
        var elemname = 'chart-data-' + i;
        var elem = document.getElementById(elemname);
        if (!elem) {
            elem = document.createElement('input');
            elem.id = elemname;
            elem.name = elemname;
            elem.value = '';
            elem.type = 'text';
            elem.size = 40;
            label = document.createElement('label');
            label.for = elemname;
            label.appendChild(document.createTextNode('Series ' + (i + 1) + ': '));
            label.appendChild(elem);
            div.appendChild(label);
        }
    }
    for (i=nSeries;; i++) {
        elem = document.getElementById('chart-data-' + i);
        if (elem) {
            div.removeChild(elem.parentNode);
        }
        else {
            break;
        }
    }
}