Myujth

I did this example https://www.mapbox.com/mapbox-gl-js/example/filter-markers/ but with polygons from geojson data. It works but when I try to load the geojson data from a file, I will get an error below

Uncaught TypeError: Cannot read property 'forEach' of undefined

mapboxgl.accessToken = '<my token>';
//var places = "type":"FeatureCollection","features":["type":"Feature","properties":"icon":"Mannheim","geometry":"type":"Polygon","coordinates":[[[8.931884765625,48.73445537176822],[9.876708984375,48.73445537176822],[9.876708984375,49.24629332459796],[8.931884765625,49.24629332459796],[8.931884765625,48.73445537176822]]],"type":"Feature","properties":"icon":"Lindau","geometry":"type":"Polygon","coordinates":[[[11.22802734375,48.36354888898689],[12.359619140624998,48.36354888898689],[12.359619140624998,49.088257784724675],[11.22802734375,49.088257784724675],[11.22802734375,48.36354888898689]]]]
var places = "yes.geojson";


var filterGroup = document.getElementById('filter-group');
var map = new mapboxgl.Map(
 container: 'map',
 style: 'mapbox://styles/mapbox/light-v9',
 center: [10.307, 50.543],
 zoom: 5.45
);

map.on('load', function() 
 // Add a GeoJSON source containing place coordinates and information.
 map.addSource("places", 
 "type": "geojson",
 "data": places
 );

 places.features.forEach(function(feature) 
 var symbol = feature.properties['icon'];
 var layerID = 'poi-' + symbol;

 // Add a layer for this symbol type if it hasn't been added already.
 if (!map.getLayer(layerID)) 
 map.addLayer(
 "id": layerID,
 "type": "fill",
 "source": "places",
 "paint": 
 "fill-color": "#2E88D6",
 "fill-opacity": 0.4
 ,
 "filter": ["==", "icon", symbol]
 );

 // Add checkbox and label elements for the layer.
 var input = document.createElement('input');
 input.type = 'checkbox';
 input.id = layerID;
 input.checked = true;
 filterGroup.appendChild(input);

 var label = document.createElement('label');
 label.setAttribute('for', layerID);
 label.textContent = symbol;
 filterGroup.appendChild(label);

 // When the checkbox changes, update the visibility of the layer.
 input.addEventListener('change', function(e) 
 map.setLayoutProperty(layerID, 'visibility',
 e.target.checked ? 'visible' : 'none');
 );
 
 );
); 

if I set var places = "yes.geojson;" it did not work anymore.