如何在 Polymer-3.x 中单击按钮时触发 Iron-ajax？

Question

I am creating a polymer element which uses iron-ajax. This will hit a public API to fetch a random fox imageUrl and dispaly in DOM.

Requirement

On clicking button , i want to make a new call to the api, this will give me new url. Currently i am using <button type="button" onClick="window.location.reload();"> . but this refreshes page.

Problem

I went through this StackOverflow solution and changed it to version-3 solution.

 class MyFox extends PolymerElement { static get template() { return html` <dom-bind> <template id="temp"> <iron-ajax auto id="dataAjax" url="" handle-as="json" on-response="handleResponse" id="apricot"> </iron-ajax> <button type="button" onClick="window.location.reload();">Next Image</button> <br> <br> <img src="[[imgUrl]]" width="300"> </template> </dom-bind> `; } static get properties() { return { prop1: { type: String, value: 'my-fox', }, imgUrl: { type: String, } }; } handleResponse(event, res) { this.imgUrl = res.response.image; } nextImg() { // new call to iron-ajax for new image var temp = document.querySelector('#temp'); temp.$.dataAjax.generateRequest(); } } window.customElements.define('my-fox', MyFox);

But i am getting the following error. listener method handleResponse not defined

Question

How to manually trigger iron-ajax on button click, so I can get new response or imageUrl and the page is not refreshed?

Answer 1

There are a couple errors in your web component

class MyFox extends PolymerElement {
  static get template() {
    return html`
          <iron-ajax
            auto
            id="dataAjax"
            url=""
            handle-as="json"
            on-response="handleResponse">
          </iron-ajax>

          <button type="button" on-tap="nextImg">Next Image</button>
          <br> <br>
          <img src="[[imgUrl]]" width="300">
    `;
  }
  static get properties() {
    return {
      prop1: {
        type: String,
        value: 'my-fox',
      },
      imgUrl: {
        type: String,
      }
    };
  }
  handleResponse(event, res) {
    this.imgUrl = res.response.image; 
  }
  nextImg() {
    // new call to iron-ajax for new image
    this.$.dataAjax.generateRequest();
  }
}

window.customElements.define('my-fox', MyFox);