如何使用TopoJSON閱讀geojson文件

Question

我正在努力調整閱讀json文件後自動調整的json文件大小。但我收到錯誤。

$.getJSON("data/cities.json", function (data) { 
     getData = topojson.feature(data, data.features); 
     console.log(getData) 
    }); 

Cities.json樣子

{ 
"type": "FeatureCollection", 
"features": [{ 
    "geometry": { 
     "type": "MultiPolygon", 
     "coordinates": [ 
      [ 
       [ 
        [-73.8283219965448, 40.8446061654002], 
        [-73.828397789942, 40.844583182304], 
        [-73.8285477331865, 40.8448132168025], 
        [-73.8284744943625, 40.8448401137412], 
        [-73.8283219965448, 40.8446061654002] 
       ] 
      ] 
     ] 
    }, 
    "type": "Feature", 
, { 
    "geometry": { 
     "type": "MultiPolygon", 
     "coordinates": [ 
      [ 
       [ 
        [-73.832361912256, 40.8488019205992], 
        [-73.832369554769, 40.8487286684528], 
        [-73.8327312374341, 40.8487518102579], 
        [-73.8327304815978, 40.8487590590352], 
        [-73.8327235953166, 40.8488250624279], 
        [-73.832361912256, 40.8488019205992] 
       ] 
      ] 
     ] 
    }, 
    "type": "Feature" 
} 


} 

我怎樣才能使用的getJSON然後通過其加載JSON數據topojson