$ tns --version
1.5.2

{
  ...
  "nativescript": {
    "id": "...",
    "tns-ios": {
      "version": "1.5.1"
    },
    "tns-android": {
      "version": "1.5.1"
    }
  },
  ...
}

var query = {
  param1: 'some value',
  param2: 'a b c d e',
};

var queryString = Object.keys(query).map(function(key) {
  return encodeURIComponent(key) + '=' + encodeURIComponent(query[key]);
}).join('&');

fetch('http://requestb.in/vbwqclvb?' + queryString).then(function(r) {
  console.log('result', r.ok);
}).catch(function(e) {
  console.log('error', e);
});

QUERYSTRING

param2: a b c d e
param1: some%20value