【一】用var 声明多个变量，比每个变量都用var快多了　　　

复制代码 代码如下:
var sScrollTop = document.body.scrollTop || document.documentElement.scrollTop,
    sWindow_h = document.documentElement.clientHeight,
    t_h = parseInt(this.getCss(this.getId('gy_photoBox_head'),'height')),
    hold_h = sWindow_h - t_h - 20,
    width = this.nImgWidth ,
    height = this.nImgHeight;　　

【二】Dom事件优化，在 window.onresize时，定义个定时器,setTimeout，可以防止事件频繁调用

复制代码 代码如下:
windowResize:function(){
            var _that = this,
                _timer = null;
            // 函数节流
            window.onresize = function(){
                clearTimeout(_timer);
                _timer = setTimeout(function(){
                    if( _that.tools.getId('gy_photoBox')){
                        _that.setBoxCss();
                    }

                },100);
            }       
        }

【三】图片加载的处理函数
复制代码 代码如下:
/*
        @ src [String] 图片的地址
        @ success [Function] 图片加载成功的回调函数
        @ error [Function] 图片加载失败的回调函数
        */
        imgLoading:function(opt){
            var _img = new Image(),
                _that = this;
            _img.onload = function(){
                _that.nImgWidth = this.width;
                _that.nImgHeight = this.height;
                if(typeof opt.success == 'function'){
                    setTimeout(function(){
                        opt.success();
                    },300);
                }
            }
            _img.onerror = function(){
                if(typeof opt.error){
                    opt.error();
                }           
            }
            // 注意：要放在onload事件下面，否则ie会出现BUG
            _img.src = opt.src;
        }

源代码：

复制代码 代码如下:
/*
author:laoguoyong
*/
(function(){
    /* -------------------------简单的选择器-----------------------
    @ 参数 [string]
    ---------------------------------------
    ★-只支持以下选择-★
    @ 支持一级选择器：如'#id','.class','p'
    @ 支持后代选择，如 '.class p','body span'
    @ 支持子元素选择，如 '.class>p','body>span'
    ----------------------------------------
    @ return [Array]
    */
    var selector = function(str){
        // 定义元素数组
        var elem = [];
        /* 私有方法
        ------------------------*/
        //返回是id的元素
        function _getId(id){
            return document.getElementById(id);
        }
        //返回存在此类名的元素-元素
        function _getByClassName(className,parent){
            var class_array = [],
                node = parent != undefined&&parent.nodeType==1"(^|\\s)"+className+"(\\s|$)");
            for(var n=0,i=node.length;n<i;n++){
                if(reg.test(node[n].className)){
                    class_array.push(node[n]);
                }
            }
            return class_array;
        }
        //一级选择，如 '#id','p','.class'
        // return [Array]
        function _getDom(s){
            var array_elem = [];
            if (s.indexOf('#')==0){
                array_elem.push(_getId(s.slice(1)));
            }
            else if(s.indexOf('.')==0){
                array_elem = array_elem.concat(_getByClassName(s.slice(1)));
            }
            else{
                var tag = document.getElementsByTagName(s);
                for(var n=0,i=tag.length;n<i;n++){
                    array_elem.push(tag[n]);
                }
            }
            return array_elem;
        }
        /*
        @ arry_elm [Array] : 元素数组，如 ['.demo','p'] ，选择的是.demo下面的p元素，至于是选择后代还是子代，请看第2个参数解释
        @ r [String] -可选（不传默认为选择后代）: '>'，是选择子代元素;
        --------------------------
        @ return [Array]
        */
        function _query(array_elem,r){
            var node = array_elem,
                type_name = node[0].match(/\#/)"(^|\\s)"+type[1]+"(\\s|$)");;
            for(var i=0,j=child.length;i<j;i++){
                var par = child[i].parentNode;
                for(var n=0;n<len;n++){
                    if(par.nodeType == 9){
                        break;
                    }
                    if(reg.test(par[type[0]])){
                        elem.push(child[i]);
                        break;                   
                    }else{
                        if(r == '>') break;
                        par = par.parentNode;
                    }       
                }
            }
        }
        /* 接口
        -----------------------*/
        var elemStr = str.replace(/(^\s+)|(\s+$)/,'');
        if(document.querySelectorAll){
            var dom = document.querySelectorAll(elemStr);
            for(var n=0,len=dom.length;n<len;n++){
                elem.push(dom[n]);
            }
        }else{
            var    split = /[\>\s]/g.exec(elemStr);
            if(split){
                var node = elemStr.split(split[0]);
                _query(node,split[0]);
            }else{
                elem = elem.concat( _getDom(elemStr) );
            }
        }
        return elem;
    }
    /* 弹窗功能构造函数
    -----------------------*/
    function LGY_photoBox(option){
        this.opt = option;
        this.oTarget = typeof option.target == 'object'"gy_photoBox_prev"></div>'+
                            '<div id="gy_photoBox_next"></div>'+
                            '<span id="gy_photoBox_close"></span>'+
                            '<div id="gy_photoBox_head">'+exHtml+'</div>'+
                            '<div id="gy_photoBox_main">'+
                                '<img id="gy_photoBox_img_loading" src="/UploadFiles/2021-04-02/blank.gif">                                 '<img id="gy_photoBox_img" />'+
                                '<div id="gy_photoBox_infor">'+
                                    '<span id="gy_photoBox_num">'+
                                        '<strong id="gy_photoBox_index"></strong>'+
                                        '/'+this.nLen+
                                    '</span>'+
                                    '<p id="gy_photoBox_title"></p>'+
                                '</div>'+
                            '</div>';
        },
        createCover:function(){
            // 创建覆盖层
            var    doc = document,
                coverHtml = doc.createElement('div');
                coverHtml.id = 'gy_photoBox_cover';
            doc.body.appendChild(coverHtml);
            //设置覆盖层的样式
            this.tools.setCss(this.tools.getId('gy_photoBox_cover'),{'height':(doc.body.scrollTop || doc.documentElement.scrollTop)+(doc.documentElement.clientHeight)+'px'});
        },
        setBoxCss:function(){
            var    doc = document,
                nScrollTop = doc.body.scrollTop || doc.documentElement.scrollTop,
                nWindow_h = doc.documentElement.clientHeight,
                eBox_head_h = this.tools.getId('gy_photoBox_head').clientHeight,
                eBox = this.tools.getId('gy_photoBox'),
                eBoxPadding = 10,
                hold_h = nWindow_h - eBoxPadding - 50 - eBox_head_h,
                width = this.nImgWidth ,
                height = this.nImgHeight;
            // alert('nWindow_h:'+nWindow_h+'-'+'eBoxPadding:'+eBoxPadding+'-'+'eBox_head_h:'+eBox_head_h);
            // 图片大小超过可见范围，进行缩放
            if(this.nImgHeight>hold_h){
                height = hold_h,
                width = Math.ceil(this.nImgWidth*(height/this.nImgHeight));
            }
            //设置盒子在整个页面居中
            this.tools.setCss(eBox,{'width':width+'px',
                                    'height':eBox_head_h + height + 'px',
                                    'margin-left':-(width+eBoxPadding)/2+'px',
                                    'top':nScrollTop+(nWindow_h-height-eBoxPadding)/2+'px'});
            this.tools.setCss(this.tools.getId('gy_photoBox_main'),{'width':width+'px','height':height + 'px'});
            //设置覆盖层的样式
            this.tools.setCss(this.tools.getId('gy_photoBox_cover'),{'height':nScrollTop+doc.documentElement.clientHeight+'px'});
        },
        removeBox:function(){
            var doc = document;
            if(this.tools.getId('gy_photoBox')){
                doc.body.removeChild(this.tools.getId('gy_photoBox'));
            }
            if(this.tools.getId('gy_photoBox_cover')){
                document.body.removeChild(this.tools.getId('gy_photoBox_cover'));
            }
            this.tools.setCss(document.documentElement,{'height':'auto','overflow-y':'auto','_overflow-y':'scroll','overflow-x':'auto'});
        },
        getData:function(){
            for(var n=0;n<this.nLen;n++){
                var src = this.oTarget[n].getAttribute('href'),
                    title = this.oTarget[n].getAttribute('title');
                this.aBigimg_src.push(src);
                if(!title) title = '';
                this.aTitle.push(title);
            }
        },
        btnIsShow:function(){
            this.tools.setCss(this.tools.getId('gy_photoBox_prev'),{'display':'block'});
            this.tools.setCss(this.tools.getId('gy_photoBox_next'),{'display':'block'});
            if(this.nIndex == 0) this.tools.setCss(this.tools.getId('gy_photoBox_prev'),{'display':'none'});
            if(this.nIndex == (this.nLen-1)) this.tools.setCss(this.tools.getId('gy_photoBox_next'),{'display':'none'});
        },
        imgChange:function(){
            var _that = this,
                _src = this.aBigimg_src[this.nIndex],
                eLoadingTips = this.tools.getId('gy_photoBox_img_loading'),
                eImg = this.tools.getId('gy_photoBox_img'),
                eTitle = this.tools.getId('gy_photoBox_title'),
                eInfor = this.tools.getId('gy_photoBox_infor');
            // 显示loading图片
            this.tools.setCss(eLoadingTips,{'display':'block'});
            this.tools.setCss(eInfor,{'display':'none'});
            // 判断左右按钮显示
            this.btnIsShow();
            // 图片加载处理
            this.imgLoading({
                'src':_src,
                'success':function(){
                    _that.tools.setCss(eLoadingTips,{'display':'none'});
                    _that.tools.setCss(eInfor,{'display':'block'});
                    // 设置真实图片路径，标题，当前页码
                    eImg.src = _src;
                    eTitle.innerHTML = _that.aTitle[_that.nIndex];
                    _that.tools.getId('gy_photoBox_index').innerHTML = (_that.nIndex+1);
                    // 设置样式
                    _that.setBoxCss();
                    // 弹窗呈现
                    _that.tools.setCss(_that.tools.getId('gy_photoBox'),{'visibility':'visible'});
                    if(_that.tools.getId('gy_photoBox_firstLoad')){
                        document.body.removeChild(_that.tools.getId('gy_photoBox_firstLoad'));
                    }
                    // 每次切换执行的回调函数
                    if(typeof _that.opt.onChange == 'function'){
                        _that.opt.onChange({'src':_src,'index':_that.nIndex,'title':_that.aTitle[_that.nIndex]});
                    }
                },
                'error':function(){
                    setTimeout(function(){
                        _that.tools.setCss(eLoadingTips,{'display':'none'});
                    },200);
                    eImg.src = 'gyPhotoBox/error.png';
                    eTitle.innerHTML = '暂无相关图片';
                    _that.nImgWidth = 400;
                    _that.nImgHeight = 300;
                    _that.setBoxCss();
                    _that.tools.setCss(_that.tools.getId('gy_photoBox'),{'visibility':'visible'});
                    if(_that.tools.getId('gy_photoBox_firstLoad')){
                        document.body.removeChild(_that.tools.getId('gy_photoBox_firstLoad'));
                    }
                }
            });
        },
        btnPrev:function(){
            var _that = this;
            this.tools.getId('gy_photoBox_prev').onclick = function(){
                _that.nIndex--;
                _that.imgChange();
            }
        },
        btnNext:function(){
            var _that = this;
            this.tools.getId('gy_photoBox_next').onclick = function(){
                _that.nIndex++;
                _that.imgChange();
            }
        },
        keyEvent:function(){
            var _that = this;
            document.onkeydown = function(e){
                var e = e || window.event;
                switch(e.keyCode){
                    case 37:{
                        if(_that.nIndex != 0&&_that.tools.getId('gy_photoBox_prev')){
                            _that.nIndex--;
                            _that.imgChange();   
                        }   
                    };break;
                    case 39 :{
                        if(_that.nIndex != (_that.nLen-1)&&_that.tools.getId('gy_photoBox_next')){
                            _that.nIndex++;
                            _that.imgChange();   
                        }           
                    };break;
                    case 27:{
                        _that.removeBox();                           
                    };break;
                }
            }
        },
        /*
        @ src [String] 图片的地址
        @ success [Function] 图片加载成功的回调函数
        @ error [Function] 图片加载失败的回调函数
        */
        imgLoading:function(opt){
            var _img = new Image(),
                _that = this;
            _img.onload = function(){
                _that.nImgWidth = this.width;
                _that.nImgHeight = this.height;
                if(typeof opt.success == 'function'){
                    setTimeout(function(){
                        opt.success();
                    },300);
                }
            }
            _img.onerror = function(){
                if(typeof opt.error){
                    opt.error();
                }           
            }
            // 注意：要放在onload事件下面，否则ie会出现BUG
            _img.src = opt.src;
        },
        firstLoad:function(src,callback){
            var _that = this,
                html = document.createElement('div');
                html.id = 'gy_photoBox_firstLoad';
            document.body.appendChild(html);
            this.tools.setCss(this.tools.getId('gy_photoBox_firstLoad'),{'top':(document.body.scrollTop || document.documentElement.scrollTop)+(document.documentElement.clientHeight/2) +'px'});
            if(typeof callback == 'function') {
                callback();
            }
        },
        windowResize:function(){
            var _that = this,
                _timer = null;
            // 函数节流
            window.onresize = function(){
                clearTimeout(_timer);
                _timer = setTimeout(function(){
                    if( _that.tools.getId('gy_photoBox')){
                        _that.setBoxCss();
                    }
                },100);
            }       
        },
        tools:function(){
            return{
                getEvent:function(e){
                    return e || window.event;
                },
                getTarget:function(e){
                    return e.target || e.srcElement;
                },
                preventDefault:function(e){
                    e.preventDefault"" src="/UploadFiles/2021-04-02/201501121054165.jpg">