Leaflet heatmap, getJSON vs hard-coded

gistfile1.js

 // don't forget to include leaflet-heatmap.js
    var heatmapArray = $.getJSON('../apis/heatmap?uri=http://nomisma.org/id/' + id);
    var testData = {
        "max": 4, "data":[ {
            "lat": 45.31859, "lng": 11.27843, "count": 1
        },
        {
            "lat": 45.03537, "lng": 11.22923, "count": 1
        },
      
            "lat": 40.4223, "lng": 15.00731, "count": 1
        },
        {
            "lat": 44.23819, "lng": 12.15277, "count": 1
        },
        {
            "lat": 42.83333, "lng": 12.83333, "count": 1
        }]
    };
    
    var baseLayer = L.tileLayer(
    'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        attribution: '...',
        maxZoom: 18
    });
    
    var cfg = {
        // radius should be small ONLY if scaleRadius is true (or small radius is intended)
        // if scaleRadius is false it will be the constant radius used in pixels
        "radius": 1,
        "maxOpacity": .8,
        // scales the radius based on map zoom
        "scaleRadius": true,
        // if set to false the heatmap uses the global maximum for colorization
        // if activated: uses the data maximum within the current map boundaries
        //   (there will always be a red spot with useLocalExtremas true)
        "useLocalExtrema": true,
        // which field name in your data represents the latitude - default "lat"
        latField: 'lat',
        // which field name in your data represents the longitude - default "lng"
        lngField: 'lng',
        // which field name in your data represents the data value - default "value"
        valueField: 'count'
    };
    
    
    var heatmapLayer = new HeatmapOverlay(cfg);
    
    var map = new L.Map('mapcontainer', {
        center: new L.LatLng(41.9, 12.5),
        zoom: 4,
        layers:[baseLayer, heatmapLayer]
    });
    
    heatmapLayer.setData(testData);