Change URL parameters and specify defaults using JavaScript

Question

I've extended Sujoy's code to make up a function.

/**
 * http://stackoverflow.com/a/10997390/11236
 */
function updateURLParameter(url, param, paramVal){
    var newAdditionalURL = "";
    var tempArray = url.split("?");
    var baseURL = tempArray[0];
    var additionalURL = tempArray[1];
    var temp = "";
    if (additionalURL) {
        tempArray = additionalURL.split("&");
        for (var i=0; i<tempArray.length; i++){
            if(tempArray[i].split('=')[0] != param){
                newAdditionalURL += temp + tempArray[i];
                temp = "&";
            }
        }
    }

    var rows_txt = temp + "" + param + "=" + paramVal;
    return baseURL + "?" + newAdditionalURL + rows_txt;
}

Function Calls:

var newURL = updateURLParameter(window.location.href, 'locId', 'newLoc');
newURL = updateURLParameter(newURL, 'resId', 'newResId');

window.history.replaceState('', '', updateURLParameter(window.location.href, "param", "value"));

Updated version that also take care of the anchors on the URL.

function updateURLParameter(url, param, paramVal)
{
    var TheAnchor = null;
    var newAdditionalURL = "";
    var tempArray = url.split("?");
    var baseURL = tempArray[0];
    var additionalURL = tempArray[1];
    var temp = "";

    if (additionalURL) 
    {
        var tmpAnchor = additionalURL.split("#");
        var TheParams = tmpAnchor[0];
            TheAnchor = tmpAnchor[1];
        if(TheAnchor)
            additionalURL = TheParams;

        tempArray = additionalURL.split("&");

        for (var i=0; i<tempArray.length; i++)
        {
            if(tempArray[i].split('=')[0] != param)
            {
                newAdditionalURL += temp + tempArray[i];
                temp = "&";
            }
        }        
    }
    else
    {
        var tmpAnchor = baseURL.split("#");
        var TheParams = tmpAnchor[0];
            TheAnchor  = tmpAnchor[1];

        if(TheParams)
            baseURL = TheParams;
    }

    if(TheAnchor)
        paramVal += "#" + TheAnchor;

    var rows_txt = temp + "" + param + "=" + paramVal;
    return baseURL + "?" + newAdditionalURL + rows_txt;
}

I think you want the query plugin.

E.g.:

window.location.search = jQuery.query.set("rows", 10);

This will work regardless of the current state of rows.

To answer my own question 4 years later, after having learned a lot. Especially that you shouldn't use jQuery for everything. I've created a simple module that can parse/stringify a query string. This makes it easy to modify the query string.

You can use query-string as follows:

// parse the query string into an object
var q = queryString.parse(location.search);
// set the `row` property
q.rows = 10;
// convert the object to a query string
// and overwrite the existing query string
location.search = queryString.stringify(q);

Quick little solution in pure js, no plugins needed:

function replaceQueryParam(param, newval, search) {
    var regex = new RegExp("([?;&])" + param + "[^&;]*[;&]?");
    var query = search.replace(regex, "$1").replace(/&$/, '');

    return (query.length > 2 ? query + "&" : "?") + (newval ? param + "=" + newval : '');
}

Call it like this:

 window.location = '/mypage' + replaceQueryParam('rows', 55, window.location.search)

Or, if you want to stay on the same page and replace multiple params:

 var str = window.location.search
 str = replaceQueryParam('rows', 55, str)
 str = replaceQueryParam('cols', 'no', str)
 window.location = window.location.pathname + str

edit, thanks Luke: To remove the parameter entirely, pass false or null for the value: replaceQueryParam('rows', false, params). Since 0 is also falsy, specify '0'.

Ben Alman has a good jquery querystring/url plugin here that allows you to manipulate the querystring easily.

As requested -

Goto his test page here

In firebug enter the following into the console

jQuery.param.querystring(window.location.href, 'a=3&newValue=100');

It will return you the following amended url string

http://benalman.com/code/test/js-jquery-url-querystring.html?a=3&b=Y&c=Z&newValue=100#n=1&o=2&p=3

Notice the a querystring value for a has changed from X to 3 and it has added the new value.

You can then use the new url string however you wish e.g using document.location = newUrl or change an anchor link etc

A modern approach to this is to use native standard based URLSearchParams. It's supported by all major browsers, except for IE where they're polyfills available

const paramsString = "site.fwx?position=1&archiveid=5000&columns=5&rows=20&sorting=ModifiedTimeAsc"
const searchParams = new URLSearchParams(paramsString);
searchParams.set('rows', 10);
console.log(searchParams.toString()); // return modified string.

you can do it via normal JS also

var url = document.URL
var newAdditionalURL = "";
var tempArray = url.split("?");
var baseURL = tempArray[0];
var aditionalURL = tempArray[1]; 
var temp = "";
if(aditionalURL)
{
var tempArray = aditionalURL.split("&");
for ( var i in tempArray ){
    if(tempArray[i].indexOf("rows") == -1){
            newAdditionalURL += temp+tempArray[i];
                temp = "&";
            }
        }
}
var rows_txt = temp+"rows=10";
var finalURL = baseURL+"?"+newAdditionalURL+rows_txt;