Get Query String Parameter in Sharepoint App

$(document).ready(function () {

//Get the URI decoded SharePoint site url from the SPHostUrl parameter.
    var spHostUrl = decodeURIComponent(getQueryStringParameter('SPHostUrl'));
    var appWebUrl = decodeURIComponent(getQueryStringParameter('SPAppWebUrl'));
    var spLanguage = decodeURIComponent(getQueryStringParameter('SPLanguage'));

});

function getQueryStringParameter(paramToRetrieve) {
    var params =
        document.URL.split("?")[1].split("&");
    for (var i = 0; i < params.length; i = i + 1) {
        var singleParam = params[i].split("=");
        if (singleParam[0] == paramToRetrieve)
            return singleParam[1];
    }
}