无法处理代码以说明javascript

Question

我是javascript新手，以前仅使用过Python编程语言。我正在使用Express / Node JS开发Web应用程序，并具有以下代码，以使用Chart js库呈现图表：

app.controller("ambientCtrl", function($scope, $http, $window, $timeout) {

  $scope.sensors = []

  $http.get('https://cors-anywhere.herokuapp.com/https://cararobot.eu/api/sensor?time_from=1550049008.4456067&time_to=1550052056.438995', {dataType: 'json'}).then(function successCallback(response) {
    var ctx = document.getElementById("myChart").getContext('2d');
    var colors = ["rgba(255,99,132,1)","rgba(54, 162, 235, 1)","rgba(255, 206, 86, 1)","rgba(75, 192, 192, 1)","rgba(153, 102, 255, 1)"];
    var unique_timestamps = [...new Set(response.data.map(item => item.timestamp))].sort(function(a, b){return a-b});
    //console.log(Object.keys(unique_timestamps).length)
    var sensor_list = [...new Set(response.data.map(item => item.sensor_id))].sort(function(a, b){return a-b});
    $scope.sensors = sensor_list;
    var temperature_datasets = [];      // Will hold final arrays of sensor readings

    for (i = 0; i < sensor_list.length; i++) {
        readings_arr =[];       // Holds the array of temperatures for one sensor
        for (j = 0; j < unique_timestamps.length; j++) {
            var result = response.data.filter(obj => {
                return (obj.timestamp === unique_timestamps[j] && obj.sensor_id === sensor_list[i])
            })
            if (typeof result[0] !== 'undefined') {
                readings_arr[j]=result[0].temp;
            } else {
                readings_arr[j]="";
            }
        }
        temperature_datasets[i] = readings_arr;
        var series = {data:temperature_datasets[i],label:sensor_list[i],
                    fill: false,
                    backgroundColor: colors[i],
                    borderColor: colors[i], // The main line color
                    borderCapStyle: 'square',
                    borderDash: [], // try [5, 15] for instance
                    borderDashOffset: 0.0,
                    borderJoinStyle: 'miter',
                    pointBorderColor: "black",
                    pointBackgroundColor: "white",
                    pointBorderWidth: 1,
                    pointHoverRadius: 8,
                    pointHoverBackgroundColor: "yellow",
                    pointHoverBorderColor: "brown",
                    pointHoverBorderWidth: 2,
                    pointRadius: 4,
                    pointHitRadius: 10,
                    spanGaps: true,

                }
          $scope.chart_dataset.push(series);
    }

    var myChart = new Chart(ctx, {
        type: 'line',
        data: {
            labels: unique_timestamps,
            datasets: $scope.chart_dataset
        },
        options: {
            scales: {
                yAxes: [{
                    ticks: {
                        beginAtZero:true
                    }
                }]
            }
        }
    });
    console.log(myChart.data);
  }, function errorCallback(response) {
    console.log("HANDLE ERROR");
  });


  console.log(myChart.data);


});

我遇到的问题是，运行请求后，我需要访问myChart.data。因此，第66行的'console.log（myChart.data）'在第72行未定义。类似地，当我尝试从请求内部将全局变量'sensors'设置为'sensor_list'时，在以后使用它，它也是未定义的。我知道这是由于javascript的异步特性引起的，但是我在努力使用回调方法来解决问题。我应该只将http请求添加到回调函数中，然后将响应数据另存为变量吗？