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POgoogle maps api real time updates with new geojson files
 

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  1. POgoogle maps api real time updates with new geojson files
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    <p>I would like to add the real time dynamic to my map, by means of passing a new local geojson file about every 3 minutes. What is the best approach to do this so that it is seamless to the end-user. I am thinking ajax and or setinterval function is the answer, but I'm not sure where to begin. If anyone knows of any examples or can offer some advice. I would greatly appreciate it.</p> <p>Thank you.</p> <p>Here is my attempt to use AJAX. I am unable to loop over the geoJSON structure. Not sure what i ma doing wrong. AJAX and javascript is still kind of foreign to me.</p> <pre><code> &lt;!DOCTYPE html&gt; &lt;html&gt; &lt;head&gt; &lt;p id="demo"&gt;coordinates&lt;/p&gt; &lt;/br&gt; &lt;p id="coords"&gt;coordinates&lt;/p&gt; &lt;style&gt; html, body, #map_canvas { margin: 0; padding: 0; height: 100%; } &lt;/style&gt; &lt;script src="https://maps.googleapis.com/maps/api/js?sensor=false&amp; libraries=visualization,MVCObject"&gt; &lt;/script&gt; &lt;script&gt; var map; // ajax request to load json data var xhr = new XMLHttpRequest(); xhr.open('GET', 'json_template.json', true); xhr.onload = function() { // sector_callback(this.responseText); //console.log(xhr.responseText); }; xhr.send(); // function to load map into body when page loads function initialize() { var kansas_city = new google.maps.LatLng(39.00495613,-94.64780668); var mapOptions = { zoom: 10, center: kansas_city, mapTypeId: google.maps.MapTypeId.TERRAIN }; map = new google.maps.Map(document.getElementById('map_canvas'), mapOptions); } // function definition to process the geoJSON data function sector_callback() { var bounds = new google.maps.LatLngBounds(); //console.log(xhr.responseText); for (var i = 0, len = features.length; i &lt; len; i++) { var coords = features[i].geometry.coordinates[0]; siteNames = features[i].properties.Name; // added for site names var path = []; //console.log(data); for ( var j = 0, len2 = coords.length; j &lt; len2; j++ ){ // pull out each set of coords and create a map object var pt = new google.maps.LatLng(coords[j][1], coords[j][0]) bounds.extend(pt); path.push(pt); //path.push(new google.maps.LatLng(coords[j][1], coords[j][0])); } var polygons = new google.maps.Polygon({ path: path, strokeColor: "#000000", strokeOpacity: 0.8, strokeWeight: 1, fillColor: "#000000", fillOpacity: 0.35, map: map }); createClickablePoly(polygons, siteNames); google.maps.event.addListener(polygons, 'mouseover', function() { var currentPolygon = this; currentPolygon.setOptions({ // setOptions is a method and properties below fillOpacity: 0.45, fillColor: "#FF0000" }) }); google.maps.event.addListener(polygons, 'mouseout', function() { var currentPolygon = this; currentPolygon.setOptions({ fillOpacity: 0.35, fillColor: "#000000" }) }); } } &lt;/script&gt; &lt;/head&gt; &lt;body onload="initialize()"&gt; &lt;div id="map_canvas"&gt;&lt;/div&gt; &lt;h2&gt;AJAX&lt;/h2&gt; &lt;div id="myDiv"&gt;&lt;/div&gt; &lt;/body&gt; &lt;/html&gt; </code></pre> <p>geoJSON:</p> <pre><code> { "type": "FeatureCollection", "features": [{ "type": "Feature", "properties": { "Name": "1_1", "Description": "" }, "geometry": { "type": "Polygon", "coordinates": [ [ [-94.963194, 39.316858], [-94.959670, 39.321990], [-94.959050, 39.321720], [-94.958460, 39.321400], [-94.957920, 39.321040], [-94.957420, 39.320640], [-94.956980, 39.320210], [-94.956250, 39.319270], [-94.955990, 39.318760], [-94.955780, 39.318240], [-94.955640, 39.317700], [-94.955570, 39.317160], [-94.955570, 39.316610], [-94.963194, 39.316858] ] ] } }, { "type": "Feature", "properties": { "Name": "214_1", "Description": "" }, "geometry": { "type": "Polygon", "coordinates": [ [ [-94.783917, 39.083417], [-94.776470, 39.084670], [-94.776340, 39.084140], [-94.776290, 39.083590], [-94.776300, 39.083040], [-94.776380, 39.082500], [-94.776530, 39.081960], [-94.777020, 39.080940], [-94.777360, 39.080460], [-94.777760, 39.080000], [-94.778210, 39.079570], [-94.778710, 39.079180], [-94.779260, 39.078830], [-94.783917, 39.083417] ] ] } }] } </code></pre>
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