get get param from url

getUrlParameter.js

function getUrlParameter(param) {
    var pageUrl = decodeURIComponent(window.location.search.substring(1)),
        urlVariables = pageUrl.split('&'),
        parameterName,
        i;

    for (i = 0; i < urlVariables.length; i++) {
        parameterName = urlVariables[i].split('=');

        if (parameterName[0] === param) {
            return parameterName[1] === undefined ? true : parameterName[1];
        }
    }
};