Ajax file upload

gistfile1.js

/*
 * Ajax file upload experiment
 */

AjaxUploadHandler = function(o){
    this._options = {
        action: '/upload.php',
        onProgress: function(fileName, loaded, total){},
        onComplete: function(fileName, response){},
        onCancel: function(id, fileName){}
    };
    $.extend(this._options, o);    
    
    this._file = null;
    this._xhr = null;
    this._loaded = 0;
};


$.extend(AjaxUploadHandler.prototype, {
    setFile: function(file){
        if (!(file instanceof File)){
            throw new Error('Passed obj in not a File (in qq.UploadHandlerXhr)');
        }
                
        this._file = file;        
    },
    getName: function(){        
        return this._file.fileName != null ? this._file.fileName : this._file.name;       
    },
    getSize: function(id){
        return this._file.fileSize != null ? this._file.fileSize : this._file.size;
    },    
    getLoaded: function(id){
        return this._loaded || 0; 
    },
    upload: function(params){
        var file = this._file,
            name = this.getName(),
            size = this.getSize();
                
        this._loaded = 0;
                                
        var xhr = this._xhr = new XMLHttpRequest();
        var self = this;
                                        
        xhr.upload.onprogress = function(e){
            if (e.lengthComputable){
                self._loaded = e.loaded;
                self._options.onProgress(name, e.loaded, e.total);
            }
        };

        xhr.onreadystatechange = function(){            
            if (xhr.readyState == 4){
                self._onComplete(xhr);                    
            }
        };

        // build query string
        params = params || {};
        params['file'] = name;
        var queryString = this._options.action + '&' + $.param(params);
        console.debug('params: ' + $.param(params));
        console.debug('querystring: ' + queryString);

        xhr.open("POST", this._options.action, true);
        xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
        xhr.setRequestHeader("X-File-Name", encodeURIComponent(name));
        xhr.setRequestHeader("Content-Type", "application/octet-stream");
        xhr.send(file);
    },
    _onComplete: function(xhr){
        if (!this._file) return;
        
        var name = this.getName();
        var size = this.getSize();
        
        this._options.onProgress(name, size, size);
                
        if (xhr.status == 200){
            this.log("xhr - server response received");
            this.log("responseText = " + xhr.responseText);
                        
            var response;
                    
            try {
                response = eval("(" + xhr.responseText + ")");
            } catch(err){
                response = {};
            }
            
            this._options.onComplete(name, response);
                        
        } else {                   
            this._options.onComplete(name, {});
        }
                
        this._file = null;
    },
    _cancel: function(id){
        this._options.onCancel(this.getName());
        
        this._file = null;
        
        if (this._xhr){
            this._xhr.abort();
            this._xhr = null;                                   
        }
    }
});