var inputNumber = document.getElementById('input-number');

html5Slider.noUiSlider.on('update', function (values, handle) {

    var value = values[handle];

    if (handle) {
        inputNumber.value = value;
    } else {
        select.value = Math.round(value);
    }
});

select.addEventListener('change', function () {
    html5Slider.noUiSlider.set([this.value, null]);
});

inputNumber.addEventListener('change', function () {
    html5Slider.noUiSlider.set([null, this.value]);
});