//圖片預(yù)加載插件
(function($){????//閉包傳遞參數(shù)
function?Preload(imgs,?options)?{
var?imgs?=?(typeof?imgs?===?'string')???[imgs]?:?imgs;??//傳入對象為字符串
var?opts?=?$.extend({},?Preload.DEFAULTS,?options);?????//將默認(rèn)的參數(shù)和傳遞進(jìn)來的參數(shù)合并-->后者覆蓋前者

if?(this.opts.order?===?'ordered')?{??????//判斷使用有序還是無序???<--?這里為什么讀不到order呢？
this._oredered();
}?else?{
this._unordered();
}
//?this._unordered();
}
Preload.DEFAULTS?=?{
order:?'unordered',?//默認(rèn)使用無序預(yù)加載
each:?null,?//?每一張圖片加載完成
all:?null?//所有圖片加載完成
};
Preload.prototype._oredered?=?function?()?{????//有序預(yù)加載
var?imgs?=?this.imgs,
opts?=?this.opts,
count=?0,
len?=?imgs.length;??????//<--這里??imgs怎么傳遞的？我這里是undefined

sortPreLoad();
function?sortPreLoad?()?{
var?imgObj?=?new?Image();

$(imgObj).on('load?error',?function?()?{
opts.each?&&?opts.each(count);?????????//存在each方法,傳入count??????
if(count?>=?len?-?1)?{????//如果圖片加載完成
opts.all?&&?opts.all();
}?else?{
sortPreLoad();
}
count++;
});
imgObj.src?=?imgs[count];
};
}
Preload.prototype._unordered?=?function?()?{?//無序加載
var?imgs?=?this.imgs,
opts?=?this.opts,
count?=?0;
alert(this.imgs)
var?len?=?imgs.length;


$.each(imgs,?function?(i,?src)?{
if(typeof?src?!=?'string'){
return?;
}
var?imgObj?=?new?Image();

$(imgObj).on('load?error',?function?()?{
opts.each?&&?opts.each(count);
if(count?>=?len?-1)?{
opts.all?&&?opts.all();
}
count++;
});
imgObj.src?=?src;
});
};

$.extend({
preload:?function?(imgs,?opts)?{
new?Preload(imgs,?opts);
}
});

})(jQuery)

preload.js:48 Uncaught TypeError: Cannot read property 'length' of undefined ? ?

at Preload._unoredered (preload.js:48) ? ?

at new Preload (preload.js:12) ? ?

at Function.preload (preload.js:72) ? ?

at index.html:100

-----

preload.js:7 Uncaught TypeError: Cannot read property 'order' of undefined ? ?

at new Preload (preload.js:7) ? ?

at Function.preload (preload.js:70) ? ?

at index1.html:74