A simple, library-independent ajax function

ajax.js

/**
 * Library-Independent AJAX Function
 * 
 * Usage:
 * --------------------------------
 * 
 * ajax(url, { ...properties... });
 *            -or-
 * ajax({ ...properties... });
 * 
 * Example:
 * --------------------------------
 * 
 * ajax({
 *    url: 'path/to/resource',
 *    type: 'POST',
 *    async: true,
 *    cache: true,
 *    data: { foo: 'bar', baz: 'qux' },
 *    success: function(data, request){
 *        ...actions on success...
 *    },
 *    error: function(request){
 *        ...actions on error...
 *    }
 * });
 * 
 */


function ajax() {
    
    "use strict";

    /** 
     * Parent object for all parameters
     */

    var xhr = {};

    /**
     * Determine call structure
     * ajax(url, { params }); or ajax({ params });
     */

    if (arguments.length === 1) {
        // All params passed as object
        xhr = arguments[0];
    } else {
        // Populate xhr obj with second argument
        xhr = arguments[1];
        // Add first argument to xhr object as url
        xhr.url = arguments[0];
    }


    /**
     * Parameters & Defaults
     */

    xhr.request = false;
    xhr.type = xhr.type || "GET";
    xhr.data = xhr.data || null;
    if (xhr.cache || !xhr.hasOwnProperty("cache")) { xhr.cache = true; } else { xhr.cache = false; }
    if (xhr.async || !xhr.hasOwnProperty("async")) { xhr.async = true; } else { xhr.async = false; }
    if (xhr.success && typeof xhr.success === "function") { xhr.success = xhr.success; } else { xhr.success = false; }
    if (xhr.error && typeof xhr.error === "function") { xhr.error = xhr.error; } else { xhr.error = false; }

    /**
     * Format xhr.data & encode values
     */

    if (xhr.data) {
        var param_count = 0,
            name,
            value,
            tmp_data = xhr.data;
        for (var param in tmp_data) {
            if(tmp_data.hasOwnProperty(param)){
                name = encodeURIComponent(param);
                value = encodeURIComponent(tmp_data[param]);
                if (param_count === 0) {
                    xhr.data = name + "=" + value;
                } else {
                    xhr.data += "&" + name + "=" + value;
                }
                param_count++;
            }
        }
        xhr.data = xhr.data;
    }

    /**
     * Appends data to URL
     * @string  data  The data to append
     */

    function formatURL(data) {
        var url_split = xhr.url.split("?");
        if (url_split.length !== 1) { 
            xhr.url += "&" + data; 
        } else { 
            xhr.url += "?" + data;
        }
    }

    /**
     * Handle xhr.data on GET request type
     */

    if (xhr.data && xhr.type.toUpperCase() === "GET") {
        formatURL(xhr.data);
    }

    /**
     * Check cache parameter, set URL param
     */

    if (!xhr.cache) {
        formatURL(new Date().getTime());
    }

    /**
     * Establish request
     */

    if (window.XMLHttpRequest) {
        // Modern non-IE
        xhr.request = new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        // Internet Explorer
        xhr.request = new ActiveXObject("Microsoft.XMLHTTP");
    } else {
        // No request object, break
        return false;
    }

    /**
     * Monitor ReadyState
     */

    xhr.request.onreadystatechange = function () {
        if (xhr.request.readyState === 4) {
            if (xhr.request.status === 200) {
                if (xhr.success) {
                    // Returns responseText and request object
                    xhr.success(xhr.request.responseText, xhr.request);
                }
            } else {
                if (xhr.error) {
                    // Returns request object
                    xhr.error(xhr.request);
                }
            }
        }
    };

    /**
     * Open Http Request connection
     */

    xhr.request.open(xhr.type, xhr.url, xhr.async);

    /**
     * Set request header for POST
     */

    if (xhr.type.toUpperCase() === "POST") {
        xhr.request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    }

    /**
     * Send data
     */

    xhr.request.send(xhr.data);

}

Can this be used with the jsonp datatype?