npm-polymer-elements/platinum-sw/platinum-sw-import-script.html

Polymer Elements package for npm

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

<script>
  /**
   * The `<platinum-sw-import-script>` element is used to import a JavaScript file that is executed
   * each time the service worker starts up.
   *
   * `<platinum-sw-import-script>` needs to be a child element of `<platinum-sw-register>`.
   *
   * A common use case is to define a custom request handler for a `fetch` event, but it can be used
   * for any type of code that you want to be executed by the service worker.
   *
   *     <platinum-sw-register auto-register>
   *       <platinum-sw-import-script href="custom-fetch-handler.js"></platinum-sw-import-script>
   *       <platinum-sw-fetch handler="customFetchHandler"
   *                          path="/(.*)/customFetch"></platinum-sw-fetch>
   *     </platinum-sw-register>
   *
   * You can specify multiple `<platinum-sw-import-script>` elements, each one corresponding to a
   * different JavaScript file. The JavaScript files will be loaded in the order in which the
   * `<platinum-sw-import-script>` elements appear. Under the hood, this results in an
   * [`importScripts()`](https://developer.mozilla.org/en-US/docs/Web/API/WorkerGlobalScope/importScripts)
   * call made from the context of the service worker.
   */
  Polymer({
    is: 'platinum-sw-import-script',

    properties: {
      /**
       * The URL of the JavaScript file that you want imported.
       *
       * Relative URLs are assumed to be
       * relative to the service worker's script location, which will almost always be the same
       * location as the page which includes this element.
       */
      href: String
    },

    _getParameters: function() {
      return new Promise(function(resolve) {
        var params = {};
        if (this.href) {
          params.importscript = this.href;
        } else {
          console.warn('The following platinum-sw-import-script element will not have any effect.' +
            ' The "href" attribute must be set.', this);
        }
        resolve(params);
      }.bind(this));
    }
  });
</script>