一个值得借鉴的插件写法

/*    Date: 2016/10/25    Author: hishion    Email: [e-mail]    Description: html5 文件上传小插件, 支持简单验证*/(function(){    var Uploadify = function (){        return this.init.apply(this, arguments);    };    Uploadify.prototype ={        /*            两个参数时:  form对象 与 config对象            一个参数时:  config对象        */        init: function(){            //传入的是form 与 config            if(arguments[0].tagName && arguments[0].nodeType === 1){                this.element = arguments[0];                this.setConfig(arguments[1] || {});            }else{                //传入config                this.setConfig(arguments[0]);            }            this.file    = this.options['file'] || this.element && this.element.querySelector('input[type=file]');            this.url     = this.options['url']  || this.element && this.element.action;            this.max     = this.options['maximum'];            this.size    = this.options['size'];            this.type    = this.options['type'];            this.cache   = {};            if(!this.file){                throw new Error("file does not exist!");            }else if(!this.url){                throw new Error("url cannot be empty!");            }else if(typeof FileReader === 'undefined'){                throw new Error('browser does not support FileReader!');            }            if(this.max > 1 && this.options.isMultiple){                this.file.setAttribute('multiple', true);            }else{                this.file.removeAttribute('multiple');            }            this.bindEvent();        },        /*            检验合法性, return null 表示无错, 否则 return 错误信息.        */        verify: function(file){            var msg = this.options.message;            var reg = new RegExp('\\b' + this.type + '\\b');            if(file.size > this.size){                return msg['size'];            }else if(reg.test(file.type) === false){                return msg['type'];            }else if(!this.options.isAllowSame && this.cache[file.lastModifiedDate-0] === 1){                return msg['same'];            }else{                this.cache[file.lastModifiedDate-0] = 1;                return null;            }        },        /*            获得上传的个数        */        getUploadNum: function(){            var attr, count = 0;            for(attr in this.cache){                if(this.cache[attr]){                    count++;                }            }            return count;        },        /*            开始上传文件,并验证        */        bindEvent: function(){            var self = this, opt = self.options, msg = opt.message,            cb  = ['abort', 'loadstart', 'progress', 'loadend'];                        function uploadstart(){                var files = this.files;                if(files.length > self.max || self.getUploadNum() >= self.max){                    opt['error'](files, msg['maximum']);                }else{                    for(var k = 0; k < files.length; k++){                        var ret = files[k], err = self.verify(ret),                        reader = new FileReader();                        if(err){                            opt['error'](ret, err);                        }else{                            switch(opt['rendAsType'].toLowerCase()){                                case 'string': reader.readAsBinaryString(files[k]);break;                                case 'text': reader.readAsText(files[k]);break;                                default: reader.readAsDataURL(files[k]);                            }                        }                        for(var i = 0;  i < cb.length; i++){                            reader.addEventListener(cb[i], opt[cb[i]], false);                        }                        (function(ret){                            reader.addEventListener('error', function(e){                                opt['error'](ret, err || msg['other']);                            }, false);                            reader.addEventListener('load', function(e){                                self.ajaxUpload(ret);                                opt['load']( e, ret);                            })                        }(ret));                    }                }            }            if(opt.dropElement){                self.bindDropEvent(uploadstart);            }                        self.on(self.file, 'change', function(){                uploadstart.call(this);                if(self.options.isAllowSame){                    this.dataValue = this.value;                    this.value     = '';                }            });        },        /*绑定拖拽上传事件*/        bindDropEvent: function(uploadstart){            var opt = this.options;            this.on(document, 'dragenter', opt.dragenter);            this.on(document, 'dragleave', opt.dragleave);            this.on(opt.dropElement, 'dragover', function(e){                e.preventDefault();                opt.dragover.call(this, e);            });            this.on(opt.dropElement, 'drop', function(e){                e.preventDefault();                e.stopPropagation();                uploadstart.call(e.dataTransfer);                opt.drop.call(this, e);            });        },        /*ajax 上传*/        ajaxUpload:  function(file){            var self = this;            var xhr  = new XMLHttpRequest();            var xhrData = self.element ? new FormData(self.element) : new FormData();            xhr.lastModified = file.lastModified;            xhr.onreadystatechange = function(){                var response = this.responseText;                if(this.readyState == 4){                    if(this.status < 300 && this.status >= 200){                        self.options.uploadSuccess.call(this, response);                    }else{                        self.cache[this.lastModified] = null;                        self.options.uploadFailed.call(this);                    }                }                if(!this.once){                    this.once = true;                    self.options.uploadComplete();                }            };            xhrData.append(self.options.uploadName || self.file.name, file);             xhr.open("POST", self.url, true);                xhr.send(xhrData);        },        on: function(obj, event, callback){            return obj.addEventListener(event, callback, false);        },        setConfig: function(config){            var options = {                //input file控件对象                file: '',                //上传类型                type: 'image',                //上传最多个数                maximum: 5,                //文件大小 2M                size: 1024*1024*2,                //html5中reader对象解析类型 可选 [string | text | url]                rendAsType: 'url',                //上传时后端 接收的 name                uploadName: '',                //上传地址                url: '',                //错误提示信息!                message: {                    type: '类型不对!',                    size: '文件太大',                    maximum: '上传文件数量太多!',                    same: '不能上传相同的文件!',                    other: '其它网络错误!'                },                //是否多选                isMultiple: true,                //是否允许提交重复的文件                isAllowSame: false,                //文件拖拽上传区域对象 null表示不支持                dropElement: null,                //文件拖拽dragenter事件回调                dragenter: function(){},                //文件拖拽dragleave事件回调                dragleave: function(){},                //文件拖拽dragover事件回调                dragover: function(){},                //文件拖拽drop事件回调                drop: function(){},                //ajax上传成功 回调                uploadSuccess: function(){},                //ajax上传失败 回调                uploadFailed: function(){},                //ajax上传完成                uploadComplete: function(){}            }, attr,             /*数组中 各种回调 */            cb = ['abort', 'error', 'loadstart', 'progress', 'load', 'loadend'];            for(var i = 0, len = cb.length; i < len; i++){                options[cb[i]] = function(){};            }            for(attr in config){                  if(options.hasOwnProperty(attr)){                    options[attr] = config[attr];                }            };            this.options = options;        }    };    window.mbUploadify = Uploadify;}());