::this.handleClick
中的双冒号有什么作用?它是如何工作的?我猜测它是this.handleClick.bind(this)
return <Map ref='map'
center={this.state.latlng}
zoom={13}
onClick={::this.handleClick}
onLocationfound={::this.handleLocationFound}
length={4}>
<TileLayer
url='http://{s}.tile.osm.org/{z}/{x}/{y}.png'
attribution='© <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
/>
{marker}
</Map>;
https://github.com/PaulLeCam/react-leaflet/blob/master/example/events.js#L39-L40