Parse a URL to map query parameters to their values

queryVals.js

// Map URL query items to their values
// e.g. ?referrer=https... -> queryVals[referrer] returns 'https...'
var queryVals = (function (a) {
  if (a === '') return {}
  var b = {}
  for (var i = 0; i < a.length; ++i) {
    var p = a[i].split('=', 2)
    if (p.length === 1) {
      b[p[0]] = ''
    } else {
      b[p[0]] = decodeURIComponent(p[1].replace(/\+/g, ' '))
    }
  }
  return b
})(window.location.search.substr(1).split('&'))