js cross domain request (script src)

xdr.js

/*
    cross domain request ( script src)

    todo:
      - Исправить вызов события complete
      - Не создавать объект запроса сразу, а искать в пуле и инициализировать
        найденный актуальными значениями полей объекта xdr и входными параметрами
        ( или создавать новый, если не был найден )
      - Исправить удаление переменной результата ( сейчас удаляется весь объект,
        с которого начинается путь к ней )

    @created: 4.05.12
    @author: swvitaliy ([email protected])

*/

var xdr = xdr || {}

;(function(xdr)
{
    function XdrRequest(config)
    {
        var defaults =
        {
            container:'head',
            scriptClass:'xdr',
            timeout: 30,    // seconds
            waitDelay: 50   // milliseconds
        };

        var now = (new Date()).getTime();

        this.scriptClass = config.scriptClass || defaults.scriptClass;
        this.proxyUrl = config.proxyUrl;
        this.requestUri = config.uri;
        this.requestData = config.data;
        this.timeout = config.timeout || defaults.timeout;
        this.container = config.container || defaults.container;
        this.responseVarName = config.responseVarName.replace('.', '_');
        this.waitDelay = config.waitDelay || defaults.waitDelay;

        this.events =
        {
            success:config.success || null,
            complete:config.complete || null,
            error:config.error || null,
            continue:config.continue || null
        };

        this.context = config.context || null;

        this.init();

        if (config.start)
        {
            this.open();
        }
    }

    XdrRequest.prototype =
    {
        init: function()
        {
            this.request = { script:null };
            this.response = { body:null };
        },

        opened:function()
        {
            return this.request.script !== null;
        },

        open: function()
        {
            if ( this.opened() )
            {
                return false;
            }

            this._makeRequest();
            this._startWaiting();

        },

        _makeRequest: function()
        {
            var container = this.container,
                proxy = this.proxyUrl,
                responseVarName = this.responseVarName;

            function queryArray(name, params)
            {
                var i, r = {};
                for ( i in params)
                {
                    if (params.hasOwnProperty(i))
                    {
                       r[name + '[' + i + ']'] = params[i];
                    }
                }
                return r;
            }

            function extendObj(properties)
            {
                var i;
                for ( i in properties)
                {
                    if ( properties.hasOwnProperty(i) )
                    {
                        this[i] = properties[i];
                    }
                }

            }

            function httpBuildQuery(params)
            {
                var i, r = [];
                for ( i in params)
                {
                    if ( params.hasOwnProperty(i) )
                    {
                        r.push(i + '=' + encodeURIComponent(params[i]));
                    }
                }

                return r.join('&');
            }

            function appendScriptToContainer(uri, params, attributes)
            {
                if (typeof container === 'string')
                {
                    container = $(container);
                }

                if (container instanceof jQuery)
                {
                    container = container.get(0);
                }

                params = queryArray('query', params);
                params = httpBuildQuery(params);

                var script= document.createElement('script');
                script.type= 'text/javascript';
                script.src= proxy + '?responseVarName=' + responseVarName + '&uri=' + uri + '&' + params;

                if (attributes)
                {
                    extendObj.apply(script, [attributes]);
                }

                container.appendChild(script);
                return script;
            }

            this.request.script =
                    appendScriptToContainer(encodeURIComponent(this.requestUri), this.requestData,
                            {
                                class:this.scriptClass,
                                id:this.scriptClass + '_' + (new Date()).getTime()
                            });

        },

        _startWaiting: function()
        {
            var thisObj = this,
                startTime = (new Date()).getTime(),
                timeout = this.timeout,
                responseVar = this.responseVarName,
                response = this.response,
                events = this.events,
                context = this.context;

            if ( eval( 'window.' + responseVar ) !== undefined )
            {
                throw "xdr.Request.open variable \"" + 'window.' + responseVar + "\" already exists";
            }

            function sendEvent(ev)
            {
                if ( !events.hasOwnProperty(ev) )
                {
                    throw 'xdr.XdrRequest - send undefined event ({ev})'.replace('{ev}', ev)
                }

                if ( !events[ev] )
                {
                    return false;
                }

                var evArgs = [].slice.apply(arguments, [1]);
                events[ev].apply(context, [thisObj].concat(evArgs));

                return true;
            }

            function waitForResponse()
            {
                var val = eval( 'window.' + responseVar );
                if ( val !== undefined )
                {
                    response.body = val;

                    sendEvent('complete');

                    thisObj.close();

                    sendEvent('success', val);

                    return true;
                }

                var now = (new Date()).getTime();
                if ( (now - startTime) / 1000 >= timeout )
                {
                    sendEvent('complete');

                    thisObj.close();

                    sendEvent('error', { errorType: 'timeout' });

                }
                else
                {
                    sendEvent('continue');
                    setTimeout(waitForResponse, this.waitDelay);
                }

                return false;
            }

            waitForResponse();

        },

        close: function()
        {
            if ( !this.opened() )
            {
                return false;
            }

            this._removeResponseVar();

            var $scriptRequest = $(this.request.script);
            if ( !$scriptRequest.length )
            {
                return false;
            }

            $scriptRequest.remove();
            this.request.script = null;

            return true;
        },

        _removeResponseVar: function()
        {
            var name, str = this.responseVarName,
                a = str.indexOf('.'),
                b = str.indexOf('['),
                pos = [];

            if ( a >= 0 ) pos.push(a);
            if ( b >= 0 ) pos.push(b);

            name = ( pos.length === 0 ) ? str :
                    str.slice(0, Math.max.apply(null, pos));

            delete window[name];

            return true;
        }
    };

    /* api functions & properties */

    xdr.timeout = 30;
    xdr.scriptClass = 'xdr_' + (new Date()).getTime();
    xdr.container = 'head';
    xdr.proxyUrl = 'http://your_domain.com/proxy/url/';
    xdr.responseVarName = 'replaceThisLineInTheNameOfTheVariableResponse';
    xdr.waitDelay = 50;

    xdr.Request = XdrRequest;
    xdr.requests = [];

    xdr.makeRequest = function(uri, data, success, error)
    {
        var request = new XdrRequest({

            timeout:this.timeout,
            scriptClass:this.scriptClass,
            container:this.container,
            proxyUrl:this.proxyUrl,
            responseVarName:this.responseVarName + (new Date).getTime() + Math.round(9999999999999 * Math.random()),
            waitDelay:this.waitDelay,

            uri:uri,
            data:data,
            success:success,
            error:error,
            start:true

        });
        this.requests.push(request);
        return request;
    };

})(xdr);