Simple, pure JavaScript HTTP Get function (IE8+, Chrome, Safari, Firefox, PhoneGap/Cordova)

javascript-http-get.js

/**
 * GET contents of a URL
 * @access private
 * @param {string} url - url to get
 * @param {function} error - function to call if there is an error
 * @param {function} callback - function to call if success
 * @returns {void}
 */
function httpGet(url, error, callback) {

    var xhr = new XMLHttpRequest();

    xhr.open('GET', url);
    xhr.withCredentials = true;
    xhr.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
    xhr.setRequestHeader('Content-Type', 'application/json');
    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4) {
            if (xhr.status === 200 || (xhr.status === 0 && xhr.responseText !== '')) {
                callback({
                    url: url,
                    status: 200,
                    body: xhr.responseText || ''
                });
            }
            else {
                error({
                    url: url,
                    status: xhr.status,
                    body: xhr.responseText || ''
                });
            }
        }
    };

    xhr.send();
}