Change URL parameters

Question

I have this URL:

site.fwx?position=1&archiveid=5000&columns=5&rows=20&sorting=ModifiedTimeAsc

what I need is to be able to

Answer 1

Here I have taken Adil Malik's answer and fixed the 3 issues I identified with it.

/**
 * Adds or updates a URL parameter.
 *
 * @param {string} url  the URL to modify
 * @param {string} param  the name of the parameter
 * @param {string} paramVal  the new value for the parameter
 * @return {string}  the updated URL
 */
self.setParameter = function (url, param, paramVal){
  // http://stackoverflow.com/a/10997390/2391566
  var parts = url.split('?');
  var baseUrl = parts[0];
  var oldQueryString = parts[1];
  var newParameters = [];
  if (oldQueryString) {
    var oldParameters = oldQueryString.split('&');
    for (var i = 0; i < oldParameters.length; i++) {
      if(oldParameters[i].split('=')[0] != param) {
        newParameters.push(oldParameters[i]);
      }
    }
  }
  if (paramVal !== '' && paramVal !== null && typeof paramVal !== 'undefined') {
    newParameters.push(param + '=' + encodeURI(paramVal));
  }
  if (newParameters.length > 0) {
    return baseUrl + '?' + newParameters.join('&');
  } else {
    return baseUrl;
  }
}