urlFor vs generateURL

controllers.index.js

import Ember from 'ember';

export default Ember.Controller.extend({
  routerService: Ember.inject.service('router'),
  
  routingService: Ember.inject.service('-routing'),
  
  queryParams: ['page'],
  
  page: 0,
});

controllers.index.sub-route\.js

import Ember from 'ember';

export default Ember.Controller.extend({
  routerService: Ember.inject.service('router'),
  
  routingService: Ember.inject.service('-routing'),
  
  urlByRouter: Ember.computed(function() {
    return this.get('routerService').urlFor('index');
  }),
  
  urlByRoutingWithoutEmptyObject: Ember.computed(function() {
    return this.get('routingService').generateURL('index', []);
  }),
  
  urlByRoutingWithEmptyObject: Ember.computed(function() {
    return this.get('routingService').generateURL('index', [], {});
  })
});

router\.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('index', {path: ''}, function () {
        this.route('sub-route');
  });
});

export default Router;

templates.index.hbs

<LinkTo @route="index.sub-route" @query={{hash page=3}}>Go to sub route with page=3</LinkTo>

{{outlet}}

templates.index.sub-route\.hbs

<dl>
  <dt>URL by Router Service</dt>
  <dd>{{urlByRouter}}</dd>
  
  <dt>URL by Routing Service (without empty queryParams object)</dt>
  <dd>{{urlByRoutingWithoutEmptyObject}}</dd>
  
  <dt>URL by Routing Service (with empty queryParams object)</dt>
  <dd>{{urlByRoutingWithEmptyObject}}</dd>
</dl>

twiddle.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}