Simple image preloader uses jQuery

jquery.preload.js

(function($) {
  
	$.fn.preload = function(forPreload, options) {
        
        var settings = $.extend({
			debug : false,
			percentage : {
				textCnt : '',
				lineCnt : ''
			},
			onBuild: $.noop,
			onComplete : $.noop
        }, options);
 
        var items = new Array(),
        	errors = new Array(),
        	success = new Array(),
        	current = 0,
        	root = this,
        	// all methods
        	methods = {
        		run : function() {
        			settings.onBuild();
        			// if no items, please exit..
        			if (!forPreload || forPreload.length == 0)
        				return methods.loadComplete();
        			items = forPreload;
        			// go
        			for (var i = 0; i < items.length; i++) {
						methods.loadImg(items[i]);
					}
 
        		},
        		loadImg : function(url) {
        			// loading...
					var imgLoad = new Image();
					$(imgLoad)
						.load(function() {
							success.push($(this).attr('src'))
							methods.completeLoading();
						})
						.error(function() {
							errors.push($(this).attr('src'));
							methods.completeLoading();
						})
					.attr('src', url);
				},
				completeLoading : function() {
					current++;
					// get current percentage
					var percent = Math.round((current / items.length) * 100);
					// update percents
					methods.updatePercents(percent);					
					// stop or continue
					if(current >= items.length) {
						current = items.length;
						if (settings.debug) {
							methods.debug();
						}
						methods.loadComplete();
					}
				},
				loadComplete: function() {
					methods.updatePercents(100, settings.onComplete.call(root))
				},
				updatePercents: function(percent, callback) {
					$(settings.percentage.lineCnt)
						.stop()
						.animate(
							{ 
								width: percent + '%'
							},
							100,
							function() { 
								if (callback) callback()
							}
						);
					$(settings.percentage.textCnt).text(percent+"%");
				},
				debug: function() {
					if (!$.browser.msie) {
						console.log('Preloader Debugger\n==================');
						// success
						console.groupCollapsed('Successful load',success.length,'images')
							if (success.length==0) {
								console.log('Global fail... =(');
							} else {
								$.each(success, function(i,v) {
									console.log(v)
								})
							}
						console.groupEnd();
						// errors
						console.group('Error load',errors.length,'images')
							if (errors.length==0) {
								console.log('No errors');
							} else {
								$.each(errors, function(i,v) {
									console.log(v)
								})
							}
						console.groupEnd();
					}
				}
	        }
 
		methods.run();
 
        return this;
    };
 
})(jQuery);

jquery.preload.min.js

(function($){$.fn.preload=function(forPreload,options){var settings=$.extend({debug:false,percentage:{textCnt:"",lineCnt:""},onBuild:$.noop,onComplete:$.noop},options);var items=new Array,errors=new Array,success=new Array,current=0,root=this,methods={run:function(){settings.onBuild();if(!forPreload||forPreload.length==0)return methods.loadComplete();items=forPreload;for(var i=0;i<items.length;i++)methods.loadImg(items[i])},loadImg:function(url){var imgLoad=new Image;$(imgLoad).load(function(){success.push($(this).attr("src"));methods.completeLoading()}).error(function(){errors.push($(this).attr("src"));methods.completeLoading()}).attr("src",url)},completeLoading:function(){current++;var percent=Math.round(current/items.length*100);methods.updatePercents(percent);if(current>=items.length){current=items.length;if(settings.debug)methods.debug();methods.loadComplete()}},loadComplete:function(){methods.updatePercents(100,settings.onComplete.call(root))},updatePercents:function(percent,callback){$(settings.percentage.lineCnt).stop().animate({width:percent+"%"},100,function(){if(callback)callback()});$(settings.percentage.textCnt).text(percent+"%")},debug:function(){if(!$.browser.msie){console.log("Preloader Debugger\n==================");console.groupCollapsed("Successful load",success.length,"images");if(success.length==0)console.log("Global fail... =(");else $.each(success,function(i,v){console.log(v)});console.groupEnd();console.group("Error load",errors.length,"images");if(errors.length==0)console.log("No errors");else $.each(errors,function(i,v){console.log(v)});console.groupEnd()}}};methods.run();return this}})(jQuery);