ES2017 （ES8）

利用object .entries()，它返回对象的[key, value]对数组。例如，对于{a: 1, b: 2}，它将返回[['a'， 1]， ['b'， 2]]。只有IE不支持(将来也不会)。

代码:

const buildURLQuery = obj =>
      Object.entries(obj)
            .map(pair => pair.map(encodeURIComponent).join('='))
            .join('&');

例子:

buildURLQuery({name: 'John', gender: 'male'});

结果:

"name=John&gender=male"

不，我认为标准JavaScript没有内置这个功能，但Prototype JS有这个功能(当然大多数其他JS框架也有，但我不知道它们)，他们称之为序列化。

I can reccomend Prototype JS, it works quite okay. The only drawback I've really noticed it it's size (a few hundred kb) and scope (lots of code for ajax, dom, etc.). Thus if you only want a form serializer it's overkill, and strictly speaking if you only want it's Ajax functionality (wich is mainly what I used it for) it's overkill. Unless you're careful you may find that it does a little too much "magic" (like extending every dom element it touches with Prototype JS functions just to find elements) making it slow on extreme cases.

如果您不想使用库，这应该涵盖大多数/所有相同的表单元素类型。

function serialize(form) {
  if (!form || !form.elements) return;

  var serial = [], i, j, first;
  var add = function (name, value) {
    serial.push(encodeURIComponent(name) + '=' + encodeURIComponent(value));
  }

  var elems = form.elements;
  for (i = 0; i < elems.length; i += 1, first = false) {
    if (elems[i].name.length > 0) { /* don't include unnamed elements */
      switch (elems[i].type) {
        case 'select-one': first = true;
        case 'select-multiple':
          for (j = 0; j < elems[i].options.length; j += 1)
            if (elems[i].options[j].selected) {
              add(elems[i].name, elems[i].options[j].value);
              if (first) break; /* stop searching for select-one */
            }
          break;
        case 'checkbox':
        case 'radio': if (!elems[i].checked) break; /* else continue */
        default: add(elems[i].name, elems[i].value); break;
      }
    }
  }

  return serial.join('&');
}

现在你可以用FormData和URLSearchParams做到这一点，而不需要循环任何东西。

const formData = new FormData(form);
const searchParams = new URLSearchParams(formData);
const queryString = searchParams.toString();

不过，旧的浏览器将需要一个填充。

这并没有直接回答您的问题，但这里有一个通用函数，它将创建一个包含查询字符串参数的URL。参数(名称和值)被安全转义以包含在URL中。

function buildUrl(url, parameters){
  var qs = "";
  for(var key in parameters) {
    var value = parameters[key];
    qs += encodeURIComponent(key) + "=" + encodeURIComponent(value) + "&";
  }
  if (qs.length > 0){
    qs = qs.substring(0, qs.length-1); //chop off last "&"
    url = url + "?" + qs;
  }
  return url;
}

// example:
var url = "http://example.com/";

var parameters = {
  name: "George Washington",
  dob: "17320222"
};

console.log(buildUrl(url, parameters));
// => http://www.example.com/?name=George%20Washington&dob=17320222

对于那些喜欢jQuery的人来说，你可以使用表单插件:http://plugins.jquery.com/project/form，它包含一个formSerialize方法。