javascript - Conditionally include script for browsers -

i have such kind of script code

settimeout(function () {     $('.grayscale .inactive img').each(function () {         $(this).wrap('<div style="display:inline-block;width:' + this.width + 'px;height:' + this.height + 'px;">').clone().addclass('gotcolors').css({             'position': 'absolute',             'opacity': 0         }).insertbefore(this);         this.src = grayscale(this.src);     }).animate({opacity: 1}, 500);      $(".grayscale li").hover(function () {         $(this).find('.gotcolors').stop().animate({opacity: 1}, 200);     }, function () {         $(this).find('.gotcolors').stop().animate({opacity: 0}, 500);     }); }, 1);` 

and need in mozilla firefox, in chrome i'm having error grayscale(this.src). how can include script mozilla firefox?

you can achieve without use of library. here's how it:

if(navigator.useragent.tolowercase().indexof('firefox') > -1) {      //your code }