Change URL parameters

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);