JavaScript 学习笔记之一jQuery写法图片等比缩放以及预加载

(function() {
var yQuery = (function() {
var yQuery = function() {
return yQuery.fn.init();
};
yQuery.fn = yQuery.prototype = {
init: function() {
return this;
},
//图片等比缩放以及预加载方法申明 但是感觉这样写(return new imgResizeBox(e))很别扭 请高手赐教
imgResize: function(e) {
return new imgResizeBox(e);
}
};
//image图片处理
var imgResizeBox = function(e) {
//image参数
setting = {
imgId: "", //图片的容器的ID 比如.viewArea img
height: 0,
width: 0,
loading: "images/lightbox-ico-loading.gif"
};
$.extend(setting, e, setting); //参数替换
var images = $(setting.imgId); //获取所有图片
$(images).hide(); //隐藏
var loading = new Image(); //预加载图片
loading.className = "loading";
loading.src = setting.loading;
$(images).after(loading);
//预加载函数
var perLoading = function($this) {
var img = new Image();
img.src = $this.src;
if (img.complete) {
computeImg.call($this);
return;
};
img.onload = function() {
computeImg.call($this);
img.onload = function() { };
};

};
//图片缩放处理,以及图片显示函数
var computeImg = function() {
var m = this.height - setting.height;
var n = this.width - setting.width;
if (m > n)
this.height = this.height > setting.height ? setting.height : this.height;
else
this.width = this.width > setting.width ? setting.width : this.width;
$(this).next(".loading").remove();
$(this).show();
};
//循环调用预加载函数
return $(images).each(function() {
perLoading(this);
});
}
return yQuery;
})();
window.yQuery = window.$$ = yQuery();
})();

$(document).ready(function()
{
$$.imgResize({ imgId: ".viewArea img", height:160, width:270, loading: "https://www.jb51.net/images/2012/155618/2012062710243954.gif" });
});