display time drift of school bus realtime map

<template>

  <div class="map-container" ref="myMap"></div>

  <span>Time drift: {{ time_difference }} sec.</span>

  <!--  <div id="map-style-menu">-->

  <!--    <input id="osm-street" type="radio" name="rtoggle" value="light">-->

  <!--    <label for="osm-street">light</label>-->

    },

    bus_marker_arr: [],

    map: [],

    time_difference: 0,

    timer: {}

  }),

      console.log("bus location data fetched at " + parseInt(d.getTime() / 1000,));

      //console log the diff of report time and display time

      if (typeof this.bus_location_data_api[0].time_rt != "undefined") {

        console.log("The clock drift is " + parseInt(d.getTime() / 1000 - this.bus_location_data_api[0].time_rt) + " seconds");

        this.time_difference = parseInt(d.getTime() / 1000 - this.bus_location_data_api[0].time_rt);

        console.log("The clock drift is " + this.time_difference + " seconds");

      }

      this.update_location()

    },