Generate query string for angular.js

qs.js

/* Converts an object into a key/value par with an optional prefix. Used for converting objects to a query string */
var qs = function(obj, prefix){
  var str = [];
  for (var p in obj) {
    var k = prefix ? prefix + "[" + p + "]" : p, 
        v = obj[k];
    str.push(angular.isObject(v) ? qs(v, k) : (k) + "=" + encodeURIComponent(v));
  }
  return str.join("&");
}

qs({foo: 'bar', UTM: {a: 'b', c: 'd'}})
"foo=bar&UTM[a]=undefined&UTM[c]=undefined"

https://gist.github.com/jaf0/e919cc780848811ec480
6: v = obj[p]

for AngularJS, this way -> https://docs.angularjs.org/api/ng/service/$httpParamSerializer