timestamp-time.html

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

<dom-module id="timestamp-time">
  <template>
    <style>
      :host {
        display: block;
      }
    </style>
    {{result}}
  </template>

  <script>
    /**
     * `timestamp-time`
     * use timestamp to display time
     *
     * usage `<timestamp-time></timestamp-time>`
     *
     * ##Attributes
     * | Attribute |Datatype| Description |
     * |-----------|--------|-------------|
     * | utc | Boolean | `true` if you want to get UTC date/time |
     * | type | String | `date` or `time` or empty, if we want Date, Time or Full String|
     * @customElement
     * @polymer
     * @demo demo/index.html
     */
    class TimestampTime extends Polymer.Element {
      static get is() { return 'timestamp-time'; }
      static get properties() {
        return {
          timestamp: {
            type: Number,
            value: function() {
              return Date.now();
            }
          },
          type: {
            type: String,
            value: ""
          },
          utc: {
            type: Boolean,
            default: false
          },
          result: {
            type: String,
            computed: '_computeReturn(timestamp, type, utc)'
          }
        };
      }

      _computeReturn(timestamp, type, utc) {
        if(!timestamp || typeof timestamp != "number") {
          return this._computeReturn(Date.now(), type, utc);
        }
        let date = new Date(timestamp),
            locale = "",
            months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];

        switch(type.toLowerCase()) {
          case "date":
            var _date = utc? (months[date.getUTCMonth()]
                                  + " "
                                  + date.getUTCDate()
                                  + ", "
                                  + date.getUTCFullYear()) : (months[date.getMonth()]
                                  + " "
                                  + date.getDate()
                                  + ", "
                                  + date.getFullYear());
            return _date;
            break;
          case "time":
            var _time = utc? (date.getUTCHours()
                                + ":"
                                + date.getUTCMinutes()
                                + ":"
                                + date.getUTCSeconds()) : (date.getHours()
                                + ":"
                                + date.getMinutes()
                                + ":"
                                + date.getSeconds());

            return _time;
            break;
          default:
            var dateString = utc ? "toGMTString":"toString";
            return date[dateString]();
        }

      }
    }

    window.customElements.define(TimestampTime.is, TimestampTime);
  </script>
</dom-module>