Answers for "convert query param filter to js object"

js object to querystring

const params = {foo:"Hi", bar:"there"}
const queryString = new URLSearchParams(params).toString();

console.log(queryString);

javascript object to query string

queryBuilder = function(obj, prefix) {
  var str = [],
    p;
  for (p in obj) {
    if (obj.hasOwnProperty(p)) {
      var k = prefix ? prefix + "[" + p + "]" : p,
        v = obj[p];
      str.push((v !== null && typeof v === "object") ?
        serialize(v, k) :
        encodeURIComponent(k) + "=" + encodeURIComponent(v));
    }
  }
  return str.join("&");
}

console.log(
serialize({
  foo: "hi there",
  bar: {
    blah: 123,
    quux: [1, 2, 3]
  }
})
);