Iron-ajax to make ajax calls to different URL endpoints

<link rel="import" href="../../bower_components/polymer/polymer.html">

<link rel="import" href="../../bower_components/iron-ajax/iron-ajax.html">
<link rel="import" href="../../bower_components/paper-input/paper-input.html">

<dom-module id="ajax-multiple">
  <template>
  <section id="content">
    <paper-input id="post" label="Post" value="{{title}}" on-blur="resolve">
    </paper-input>
    <iron-ajax auto url="{{resolveUrl}}" handle-as="json" on-response="onResponse" id="xhr"></iron-ajax>
  </section>
  </template>
  <script>
  (function(){
    'use strict';
    const url = "https://jsonplaceholder.typicode.com/posts/";
    Polymer({
      is: 'ajax-multiple',
      properties:{
        title: {
          type: String
        },
        resolveUrl: {
          type: String
        },
      },
      resolve: function(event) {
        if(event.target.value.match(/^[0-9]+$/)) {
            this.set('resolveUrl', url + event.target.value);
          }
      },
      onResponse: function(response){
        this.set('title', response.detail.response.title);
      }
  });
  </script>
</dom-module>