请编写一个 JavaScript 函数 parseQueryString，它的用途是把 URL 参数解析为一个对象，如：var url = "http://www.taobao.com/index.php?key0=0&key1=1&key2=2"; var obj = parseQueryString(url); alert(obj.key0); // 输出0

parseQueryString.js

function parseQueryString (str){
  var arr = str.replace(/^.*\?/, '').split(/[&=]/),
      res = {};
  if (arr.length % 2 !== 0) return;
  for (var i = arr.length - 1; i > 0; i -= 2) {
    res[arr[i-1]] = arr[i];
  }
  return res;
}

var url = "http://www.taobao.com/index.php?key0=0&key1=1&key2=2";

var obj = parseQueryString(url);

console.log(obj);