Add or update query string parameter

pQuery.coffee

### Add / Update a key-value pair in the URL query parameters ###
updateUrlParameter = (uri, key, value)->
  # Remove the hash part before operating on the uri
  i = uri.indexOf('#')
  hash = if i == -1 then '' else uri.substr(i)
  uri = if i == -1 then uri else uri.substr(0, i)

  re = new RegExp("([?&])" + key + "=.*?(&|$)", "i")
  separator = if uri.indexOf('?') != -1 then "&" else "?"
  if uri.match(re)
    uri = uri.replace(re, '$1' + key + "=" + value + '$2')
  else
    uri = uri + separator + key + "=" + value

  return uri + hash # finally append the hash as well

pQuery.js

// Add / Update a key-value pair in the URL query parameters
function updateUrlParameter(uri, key, value) {
    // remove the hash part before operating on the uri
    var i = uri.indexOf('#');
    var hash = i === -1 ? ''  : uri.substr(i);
         uri = i === -1 ? uri : uri.substr(0, i);

    var re = new RegExp("([?&])" + key + "=.*?(&|$)", "i");
    var separator = uri.indexOf('?') !== -1 ? "&" : "?";
    if (uri.match(re)) {
        uri = uri.replace(re, '$1' + key + "=" + value + '$2');
    } else {
        uri = uri + separator + key + "=" + value;
    }
    return uri + hash;  // finally append the hash as well
}