(function($) {
 var currentRadius, multiplier;

 function parseOptions(options) {
 return {
 RADIUS: (options.radius || 20),
 DURATION: (options.duration || 500),
 TEXT_COLOR: (options.textColor || '#fff'),
 HALO_COLOR: (options.haloColor || '#777')
 }
 }

 function currentRadius(elem) {
 if (prop = elem.style['text-shadow']) {
 return parseInt(prop.match(/0 0 (\d+)px/));
 } else {
 return 0;
 }
 }

 function stepTextShadow(fx) {
 if (fx.state == 0) {
 fx.start = currentRadius(fx.elem);
 }

 updatedRadius = fx.end.begin ?
 Math.max(Math.min(parseInt(fx.end.radius * fx.pos))) :
 Math.max(Math.min(parseInt(fx.end.radius - (fx.end.radius * fx.pos))))

 if (fx.end.begin || (fx.state < 1)) {
 fx.elem.style['text-shadow'] = fx.end.color + ' 0 0 ' + updatedRadius + 'px';
 } else {
 fx.elem.style['text-shadow'] = 'none';
 }
 }

 function addGlow(opts) {
 var opts = parseOptions(opts || { });

 function startGlow() {
 $(this).animate({
 color: opts.TEXT_COLOR,
 textShadow: {
 begin: true,
 color: opts.HALO_COLOR,
 radius: opts.RADIUS
 }
 }, opts.DURATION);
 }

 function startFade() {
 $(this).animate({
 color: $(this).data('glow.originColor'),
 textShadow: {
 begin: false,
 color: opts.HALO_COLOR,
 radius: opts.RADIUS
 }
 }, opts.DURATION);
 }

 with($(this)) {
 bind('mouseenter', startGlow);
 bind('mouseleave', startFade);
 data('glow.originColor', css('color'));
 }

 return this;
 }

 $.fx.step['textShadow'] = stepTextShadow;
 $.fn.addGlow = addGlow;
})(jQuery);