Adding a parameter to the URL with JavaScript

Question

In a web application that makes use of AJAX calls, I need to submit a request but add a parameter to the end of the URL, for example:

Original URL:

Answer 1

This is what I use when it comes to some basic url param additions or updates on the server-side like Node.js.

CoffeScript:

###
    @method addUrlParam Adds parameter to a given url. If the parameter already exists in the url is being replaced.
    @param {string} url
    @param {string} key Parameter's key
    @param {string} value Parameter's value
    @returns {string} new url containing the parameter
###
addUrlParam = (url, key, value) ->
    newParam = key+"="+value
    result = url.replace(new RegExp('(&|\\?)' + key + '=[^\&|#]*'), '$1' + newParam)
    if result is url
        result = if url.indexOf('?') != -1 then url.split('?')[0] + '?' + newParam + '&' + url.split('?')[1]
    else if url.indexOf('#') != -1 then url.split('#')[0] + '?' + newParam + '#' + url.split('#')[1]
    else url + '?' + newParam
    return result

JavaScript:

function addUrlParam(url, key, value) {
    var newParam = key+"="+value;
    var result = url.replace(new RegExp("(&|\\?)"+key+"=[^\&|#]*"), '$1' + newParam);
    if (result === url) { 
        result = (url.indexOf("?") != -1 ? url.split("?")[0]+"?"+newParam+"&"+url.split("?")[1] 
           : (url.indexOf("#") != -1 ? url.split("#")[0]+"?"+newParam+"#"+ url.split("#")[1] 
              : url+'?'+newParam));
    }
    return result;
}

var url = "http://www.example.com?foo=bar&ciao=3&doom=5#hashme";
result1.innerHTML = addUrlParam(url, "ciao", "1");