parse query string into handy map

gistfile1.js

function searchmap(separator) {
  var map = {};
  (location.search || '')
      .split("&")
      .forEach(function(x) { 
        var kv = x.split('='), k = kv[0], v = decodeURIComponent(x.substr(k + 1));
        if (separator === undefined)
          if (map[k])
            map[k] = [v];
          else
            map[k].push(v);
        else
          map[k] = map[k] ? map[k] + separator + v : v;
      });        
  return map;
}