http-ping/http-ping.html at master · telecomsante/http-ping · GitHub

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

<!--
# http-ping
Ping http(s) url and retrieve the status and delay

The component use the fetch API, so use it with recent browser.

The component has no GUI.

@demo demo/index.html
-->

<dom-module id="http-ping">

  <script>
    Polymer({

      is: 'http-ping',

      properties: {
        /**
         * The url to ping
         * @type {String}
         */
        url: {
          type: String,
          value: 'https://www.google.com',
        },
        /**
         * requests interval in milliseconds
         *
         * be aware to set an interval bigger that the timeout.
         *
         * @type {Number}
         */
        interval: {
          type: Number,
          value: 2000,
          observer: '_intervalChanged',
        },
        /**
         * Timeout in milliseconds before declaring the url unreachable
         * @type {Number}
         */
        timeout: {
          type: Number,
          value: 1000,
        },

        /**
         * Status of the connection
         * @type {Boolean}
         */
        status: {
          type: Boolean,
          value: false,
          readOnly: true,
          notify: true,
          reflectToAttribute: true,
        },

        /**
         * Delay of the ping in ms
         * @type {String}
         */
        delay: {
          type: Number,
          value: null,
          readOnly: true,
          notify: true,
          reflectToAttribute: true,
        },
      },

      /**
       * restart the loop when the value of interval change
       * @method _intervalChanged
       * @return {none}
       */
      _intervalChanged: function() {
        if(this._loop) {
          clearInterval(this._loop);
        }
        this._loop = setInterval(this._httpPing.bind(this), this.interval);
      },

      /**
       * do the ping.
       *
       * @method _httpPing
       * @return {none}
       */
      _httpPing: function() {
        const start = new Date();
        let timeout = new Promise((resolve, reject) => {
          setTimeout(reject, this.timeout, 'request timed out');
        });
        let ping = fetch(`${this.url}/?${+ new Date()}`, { mode:'no-cors' } )
            .then(response => {
              return new Date() - start;
            });
        Promise.race([timeout, ping])
          .then(delay => {
            if(!this.status) {
              /**
              * Fired when the connection state changes.
              *
              * @event ping-status
              * @param {Boolean} status the connection status
              */
              this.fire('ping-status', {status: true});
            }
            this._setStatus(true);

            /**
            * Fired when a ping is done.
            *
            * @event ping-delay
            * @param {String} url the url to ping.
            * @param {Number} delay the delay of the ping.
            */
            this.fire('ping-delay', { url: this.url, delay: delay });
            this._setDelay(delay);
          })
          .catch( err => {
            if(!this.status) {
              this.fire('ping-status', {status: false});
            }
            this._setStatus(false);
            this._setDelay(null);
            this.fire('ping-delay', { url: this.url, delay: '' });
          })
      },

    });
  </script>
</dom-module>