batch.js

var $   = require('jquery');

/**
 * Packs the given requests into the batch and returns batch contents.
 * @param {Array} data Data to pack.
 * @param {string} boundary Muti-part boundary mark.
 */
var pack = function (data, boundary) {
    var body = [];

    $.each(data, function (i, d) {
        var t = d.type.toUpperCase(), noBody = ['GET', 'DELETE'], idx;

        body.push('--' + boundary);
        body.push('Content-Type: application/http; msgtype=request', '');
        body.push(t + ' ' + d.url + ' HTTP/1.1');

        /* Don't care about content type for requests that have no body. */
        if (noBody.indexOf(t) < 0) {
            body.push('Content-Type: ' + (d.contentType || 'application/json; charset=utf-8'));
        }

        body.push('Host: ' + location.host);

        // add in custom headers to the batch if there are any
        if (d.hasOwnProperty('headers')) {
            for (idx in d.headers) {
                if (!d.headers.hasOwnProperty(idx)) {
                    continue;
                }
                body.push(idx + ': ' + d.headers[idx]);
            }
        }

        body.push('', d.data ? JSON.stringify(d.data) : '');
    });

    body.push('--' + boundary + '--', '');

    return body.join('\r\n');
}

/**
 * Unpacks the given response and passes the unpacked data to the original callback.
 * @param {object} xhr jQuery XHR object.
 * @param {string} status Response status.
 * @param {Function} complete A callback to be executed upon unpacking the response.
 */
var unpack = function (xhr, status, complete) {
    var lines = xhr.responseText.split('\r\n'),
        boundary = lines[0], data = [], d = null;

    $.each(lines, function (i, l) {
        if (l.length) {
            if (l.indexOf(boundary) == 0) {
                if (d) data.push(d);
                d = {};
            } else if (d) {
                if (!d.status) {
                    d.status = parseInt((function (m) {
                        return m || [0, 0];
                    })(/HTTP\/1.1 ([0-9]+)/g.exec(l))[1], 10);
                } else if (!d.data) {
                    try {
                        d.data = JSON.parse(l);
                    } catch (ex) { }
                }
            }
        }
    });

    complete.call(this, xhr, status, data);
}

module.exports = {
    ajaxBatch: function (params) {
        var boundary = new Date().getTime().toString();

        $.ajax({
            type: 'POST',
            url: params.url,
            dataType: 'json',
            headers: params.headers,
            data: pack(params.data, boundary),
            contentType: 'multipart/mixed; boundary="' + boundary + '"',
            complete: params.complete ?
                function (xnr, status) { unpack(xnr, status, params.complete); } :
                null
        });
    }
};