JavaScript - Get URL Query Params

get-url-params.js

/**
 * Returns a bare object of the URL's query parameters.
 * You can pass just a query string rather than a complete URL.
 * The default URL is the current page.
 */
function getUrlParams (url) {
    // http://stackoverflow.com/a/23946023/2407309
    if (typeof url == 'undefined') {
        url = window.location.search
    }
    var url = url.split('#')[0] // Discard fragment identifier.
    var urlParams = {}
    var queryString = url.split('?')[1]
    if (!queryString) {
        if (url.search('=') !== false) {
            queryString = url
        }
    }
    if (queryString) {
        var keyValuePairs = queryString.split('&')
        for (var i = 0; i < keyValuePairs.length; i++) {
            var keyValuePair = keyValuePairs[i].split('=')
            var paramName = keyValuePair[0]
            var paramValue = keyValuePair[1] || ''
            urlParams[paramName] = decodeURIComponent(paramValue.replace(/\+/g, ' '))
        }
    }
    return urlParams
} // getUrlParams

Here's another one, the computational effort is less because it doesn't use regular expressions:

function getUrlParameter (parameterName) {
    var result = null, tmp = [];
    var items = location.search.substr(1).split("&");
    for (var index = 0; index < items.length; index++) {
        tmp = items[index].split("=");
        if (tmp[0] === parameterName) result = decodeURIComponent(tmp[1]);
    }
    return result;
}