这里有一个简单的答案，在转换过程中同时处理字符串和数组。

jsonToQueryString: function (data) {
        return Object.keys(data).map((key) => {
            if (Array.isArray(data[key])) {
                return (`${encodeURIComponent(key)}=${data[key].map((item) => encodeURIComponent(item)).join('%2C')}`);
            }
            return(`${encodeURIComponent(key)}=${encodeURIComponent(data[key])}`);
        }).join('&');
    }

在ES7中，你可以用一行写:

const serialize = (obj) => (Object.entries(obj).map(i => [i[0], encodeURIComponent(i[1])].join('=')).join('&'))

const querystring=  {};

querystring.stringify = function (obj, sep = '&', eq = '=') {
  const escape = encodeURIComponent;
  const qs = [];
  let key = null;

  for (key in obj) if (obj.hasOwnProperty(key)) {
    qs.push(escape(key) + eq + escape(String(obj[key])));
  }
  return qs.join(sep);
};

例子:

const a  = querystring.stringify({a: 'all of them', b: true});
console.log(a);  // Output: a=all%20of%20them&b=true

参考答案@user187291，添加“isArray”作为参数，使要转换的JSON嵌套数组。

data : {
                    staffId : "00000001",
                    Detail : [ {
                        "identityId" : "123456"
                    }, {
                        "identityId" : "654321"
                    } ],

                }

要得到结果:

staffId=00000001&Detail[0].identityId=123456&Detail[1].identityId=654321

serialize = function(obj, prefix, isArray) {
        var str = [],p = 0;
        for (p in obj) {
            if (obj.hasOwnProperty(p)) {
                var k, v;
                if (isArray)
                    k = prefix ? prefix + "[" + p + "]" : p, v = obj[p];
                else
                    k = prefix ? prefix + "." + p + "" : p, v = obj[p];

                if (v !== null && typeof v === "object") {
                    if (Array.isArray(v)) {
                        serialize(v, k, true);
                    } else {
                        serialize(v, k, false);
                    }
                } else {
                    var query = k + "=" + v;
                    str.push(query);
                }
            }
        }
        return str.join("&");
    };

    serialize(data, "prefix", false);

这是对已接受的解的补充。这适用于对象和对象数组:

parseJsonAsQueryString = function (obj, prefix, objName) {
    var str = [];
    for (var p in obj) {
        if (obj.hasOwnProperty(p)) {
            var v = obj[p];
            if (typeof v == "object") {
                var k = (objName ? objName + '.' : '') + (prefix ? prefix + "[" + p + "]" : p);
                str.push(parseJsonAsQueryString(v, k));
            } else {
                var k = (objName ? objName + '.' : '') + (prefix ? prefix + '.' + p : p);
                str.push(encodeURIComponent(k) + "=" + encodeURIComponent(v));
                //str.push(k + "=" + v);
            }
        }
    }
    return str.join("&");
}

我还添加了objName，如果你使用对象参数，像在ASP。NET MVC动作方法。

如果你想将整个对象作为一个参数传递，例如，?filter={param1: "val1"， param2: "val2"}:

const serializeObject = (obj) => {
  let objStr = JSON.stringify(obj);

  objStr = objStr.replace(/\{/g, encodeURIComponent("{"));
  objStr = objStr.replace(/}/g, encodeURIComponent("}"));
  objStr = objStr.replace(/:/g, encodeURIComponent(":"));

  return objStr;
};

let res = serializeObject({param1: "val1", param2: "val2"});
console.log("serializeObject:", res); //%7B"param1"%3A"val1","param2"%3A"val2"%7D
console.log("serializeObject-decoded:", decodeURIComponent(res)); //{"param1":"val1","param2":"val2"}