src/jquery.nstSlider.js
function(rangeMin, rangeMax) {
            var $this = this;
            var settings = $this.data('settings');

            if (typeof settings.highlight === "undefined") {
                $.error('you cannot call highlight_range if you haven\' specified the "highlight" parameter in construction!');
            }

            // avoid empty string
            if (!rangeMin) { rangeMin = 0; }
            if (!rangeMax) { rangeMax = 0; }

            // we need to map rangeMin and rangeMax into pixels.
            var leftPx = methods.value_to_px.call($this, rangeMin),
                rightPx = methods.value_to_px.call($this, rangeMax),
                barWidth = rightPx - leftPx + $this.data('left_grip_width');

            // set position
            var $highlightPanel = $this.find(
                settings.highlight.panel_selector
            );

            $highlightPanel.css('left', leftPx + "px");
            $highlightPanel.css('width', barWidth + "px");

            // keep the latest highlighted range, because if set_range is called
            // we must be able to update the highlighting.
            $this.data('highlightedRangeMin', rangeMin);
            $this.data('highlightedRangeMax', rangeMax);

            // now decide wether the handler should be highlight
            _methods.refresh_grips_style.call($this);

            return $this;
        }
function(rangeMin, rangeMax) {
            var $this = this;
            var settings = $this.data('settings');

            if (typeof settings.highlight === "undefined") {
                $.error('you cannot call highlight_range if you haven\' specified the "highlight" parameter in construction!');
            }

            // avoid empty string
            if (!rangeMin) { rangeMin = 0; }
            if (!rangeMax) { rangeMax = 0; }

            // we need to map rangeMin and rangeMax into pixels.
            var leftPx = methods.value_to_px.call($this, rangeMin),
                rightPx = methods.value_to_px.call($this, rangeMax),
                barWidth = rightPx - leftPx + $this.data('left_grip_width');

            // set position
            var $highlightPanel = $this.find(
                settings.highlight.panel_selector
            );

            $highlightPanel.css('left', leftPx + "px");
            $highlightPanel.css('width', barWidth + "px");

            // keep the latest highlighted range, because if set_range is called
            // we must be able to update the highlighting.
            $this.data('highlightedRangeMin', rangeMin);
            $this.data('highlightedRangeMax', rangeMax);

            // now decide wether the handler should be highlight
            _methods.refresh_grips_style.call($this);

            return $this;
        }
/*
This method highlights the range of the slider apart from the
position of the slider grips.
To work well, the slider must have background color set to
transparent in the CSS or not set.