grobins/leaflet-geojson-stream

stream geojson features into a leaflet layer

leaflet-geojson-stream

Stream GeoJSON features into a Leaflet layer.

usage

With browserify

npm install --save leaflet-geojson-stream

Otherwise

curl https://raw.github.com/tmcw/leaflet-geojson-stream/master/leafletgeojsonstream.js > leafletgeojsonstream.js

api

lgs.ajax(url: string, layer: L.geoJson instance)

Request all features from a given url with hyperquest and add them incrementally to layer. Returns a stream of feature objects that also emits end on completion.

lgs.layerPipe(layer: L.geoJson instance)

Given a L.geoJson instance, return a writable stream that accepts GeoJSON Feature objects.

example

var leafletStream = require('leaflet-geojson-stream'),
    map = L.map('map').setView([0, 0], 2),
    gj = L.geoJson().addTo(map);

leafletStream.ajax('/points.geojson', gj)
    .on('end', function() {
        alert('all done!');
    });

To run the prepackaged example:

npm install
cd example
node server.js

And open http://localhost:3000/

build

npm install
npm run-script build

How

A simple abstraction on top of geojson-stream, which is in turn just a bit of sugar on JSONStream. Regular old XMLHttpRequest allows for partial replies under the magical 'status code 3'. This doesn't use WebSockets or anything else fancy.

Caveats

• Some servers will send huge chunks in their responses. This depends on a keep-alive connection with reasonable bites.
• The GeoJSON object returned by the server currently must be a FeatureCollection at its root.