function setSliderHandle(i, value) {
	var r = [null,null];
	r[i] = value;
	keypressSlider.noUiSlider.set(r);
}

// Listen to keydown events on the input field.
inputs.forEach(function(input, handle) {

	input.addEventListener('change', function(){
		setSliderHandle(handle, this.value);
	});

	input.addEventListener('keydown', function( e ) {

		var values = keypressSlider.noUiSlider.get();
		var value = Number(values[handle]);

		// [[handle0_down, handle0_up], [handle1_down, handle1_up]]
		var steps = keypressSlider.noUiSlider.steps();

		// [down, up]
		var step = steps[handle];

		var position;

		// 13 is enter,
		// 38 is key up,
		// 40 is key down.
		switch ( e.which ) {

			case 13:
				setSliderHandle(handle, this.value);
				break;

			case 38:

				// Get step to go increase slider value (up)
				position = step[1];

				// false = no step is set
				if ( position === false ) {
					position = 1;
				}

				// null = edge of slider
				if ( position !== null ) {
					setSliderHandle(handle, value + position);
				}

				break;

			case 40:

				position = step[0];

				if ( position === false ) {
					position = 1;
				}

				if ( position !== null ) {
					setSliderHandle(handle, value - position);
				}

				break;
		}
	});
});