google-maps-react

Google Map React Component Tutorial

A declarative Google Map React component using React, lazy-loading dependencies, current-location finder and a test-driven approach by the Fullstack React team.

See the demo and accompanying blog post.

Quickstart

First, install the library:

npm install --save google-maps-react

Automatically Lazy-loading Google API

The library includes a helper to wrap around the Google maps API. The GoogleApiWrapper Higher-Order component accepts a configuration object which must include an apiKey. See lib/GoogleApi.js for all options it accepts.

import {GoogleApiWrapper} from 'google-maps-react';
 
// ... 
 
export class MapContainer extends React.Component {}
 
export default GoogleApiWrapper({
  apiKey: (YOUR_GOOGLE_API_KEY_GOES_HERE)
})(MapContainer)

Sample Usage With Lazy-loading Google API:

import {Map, InfoWindow, Marker, GoogleApiWrapper} from 'google-maps-react';
 
export class MapContainer extends Component {
render() {
    return (
      <Map google={this.props.google} zoom={14}>
 
        <Marker onClick={this.onMarkerClick}
                name={'Current location'} />
 
        <InfoWindow onClose={this.onInfoWindowClose}>
            <div>
              <h1>{this.state.selectedPlace.name}</h1>
            </div>
        </InfoWindow>
      </Map>
    );
  }
}
 
export default GoogleApiWrapper({
  apiKey: (YOUR_GOOGLE_API_KEY_GOES_HERE)
})(MapContainer)

Note: Marker and InfoWindow components are disscussed below.

Additional Map Props

The Map component takes a number of optional props.

Zoom: (Shown Above) takes a number with the higher value representing a tighter focus on the map's center.

Style: Takes CSS style object - commonly width and height.

const style = {
  width: '100%',
  height: '100%'
}

initalCenter: Takes an object containing latitude and longitude coordinates. Sets the maps center upon loading.

    <Map
          google={this.props.google}
          style={style}
          initialCenter={{
            lat: 40.854885,
            lng: -88.081807
          }}
          zoom={15}
          onClick={this.onMapClicked}
        >

It also takes event handlers described below:

Events

The <Map /> component handles events out of the box. All event handlers are optional.

onReady

When the <Map /> instance has been loaded and is ready on the page, it will call the onReady prop, if given. The onReady prop is useful for fetching places or using the autocomplete API for places.

React.createClass({
  fetchPlaces: function(mapProps, map) {
    const {google} = mapProps;
    const service = new google.maps.places.PlacesService(map);
    // ... 
  },
  render: function() {
    return (
      <Map google={this.props.google}
        onReady={this.fetchPlaces}
        visible={false}>
          <Listing places={this.state.places} />
      </Map>
    )
  }
});

onClick

To listen for clicks on the <Map /> component, pass the onClick prop:

React.createClass({
  mapClicked: function(mapProps, map, clickEvent) {
    // ... 
  },
  render: function() {
    return (
      <Map google={this.props.google}
        onClick={this.mapClicked} />
    )
  }
});

onDragend

When our user changes the map center by dragging the Map around, we can get a callback after the event is fired with the onDragend prop:

React.createClass({
  centerMoved: function(mapProps, map) {
    // ... 
  },
  render: function() {
    return (
      <Map google={this.props.google}
        onDragend={this.centerMoved} />
    )
  }
});

Visibility

You can control the visibility of the map by using the visible prop. This is useful for situations when you want to use the Google Maps API without a map. The <Map /> component will load like normal. See the Google places demo

For example:

<Map google={this.props.google}
    visible={false}>
  <Listing places={this.state.places} />
</Map>

Subcomponents

The <Map /> api includes subcomponents intended on being used as children of the Map component. Any child can be used within the Map component and will receive the three props (as children):

map - the Google instance of the map
google - a reference to the window.google object
mapCenter - the google.maps.LatLng() object referring to the center of the map instance

Marker

To place a marker on the Map, include it as a child of the <Map /> component.

<Map google={this.props.google}
    style={{width: '100%', height: '100%', position: 'relative'}}
    className={'map'}
    zoom={14}>
  <Marker
    title={'The marker`s title will appear as a tooltip.'}
    name={'SOMA'}
    position={{lat: 37.778519, lng: -122.405640}} />
  <Marker
    name={'Dolores park'}
    position={{lat: 37.759703, lng: -122.428093}} />
  <Marker />
  <Marker
    name={'Your position'}
    position={{lat: 37.762391, lng: -122.439192}}
    icon={{
      url: "/path/to/custom_icon.png",
      anchor: new google.maps.Point(32,32),
      scaledSize: new google.maps.Size(64,64)
    }}
</Map>

The <Marker /> component accepts a position prop that defines the location for the position on the map. It can be either a raw object or a google.maps.LatLng() instance.

If no position is passed in the props, the marker will default to the current position of the map, i.e. the mapCenter prop.

You can also pass any other props you want with the <Marker />. It will be passed back through marker events.

Events

The <Marker /> component listens for events, similar to the <Map /> component.

onClick

You can listen for an onClick event with the (appropriately named) onClick prop.

const WithMarkers = React.createClass({
  onMarkerClick: function(props, marker, e) {
  },
  render: function() [
    return (
      <Map google={this.props.google}>
        <Marker onClick={this.onMarkerClick}
            name={'Current location'} />
      </Map>
    )
  ]
});

mouseover

You can also pass a callback when the user mouses over a <Marker /> instance by passing the onMouseover callback:

const Container = React.createClass({
  onMouseoverMarker: function(props, marker, e) {
  },
  render: function() [
    return (
      <Map google={this.props.google}>
        <Marker onMouseover={this.onMouseoverMarker}
            name={'Current location'} />
      </Map>
    )
  ]
});

Polygon

To place a polygon on the Map, set <Polygon /> as child of Map component.

render: function() {
  var triangleCoords = [
    {lat: 25.774, lng: -80.190},
    {lat: 18.466, lng: -66.118},
    {lat: 32.321, lng: -64.757},
    {lat: 25.774, lng: -80.190}
  ];
  return(
    <Map google={this.props.google}
        style={{width: '100%', height: '100%', position: 'relative'}}
        className={'map'}
        zoom={14}>
        <Polygon
          paths={triangleCoords}
          strokeColor="#0000FF"
          strokeOpacity={0.8}
          strokeWeight={2}
          fillColor="#0000FF"
          fillOpacity={0.35} />
    </Map>
  )
}

Events

The <Polygon /> component listens to onClick, onMouseover and onMouseout events.

InfoWindow

The <InfoWindow /> component included in this library is gives us the ability to pop up a "more info" window on our Google map.

The visibility of the <InfoWindow /> component is controlled by a visible prop. The visible prop is a boolean (PropTypes.bool) that shows the <InfoWindow /> when true and hides it when false.

There are two ways how to control a position of the <InfoWindow /> component. You can use a position prop or connect the <InfoWindow /> component directly to an existing <Marker /> component by using a marker prop.

//note: code formatted for ES6 here 
export class MapContainer extends Component {
  constructor(props) {
    super(props);
    this.state = {
      showingInfoWindow: false,
      activeMarker: {},
      selectedPlace: {},
    }
    
    // binding this to event-handler functions 
    this.onMarkerClick = this.onMarkerClick.bind(this);
    this.onMapClicked = this.onMapClicked.bind(this);
  }
  
  onMarkerClick: function(props, marker, e) {
    this.setState({
      selectedPlace: props,
      activeMarker: marker,
      showingInfoWindow: true
    });
  },
 
  onMapClicked: function(props) {
    if (this.state.showingInfoWindow) {
      this.setState({
        showingInfoWindow: false,
        activeMarker: null
      })
    }
  },
 
  render: function() {
    return (
      <Map google={this.props.google}
          onClick={this.onMapClicked}>
        <Marker onClick={this.onMarkerClick}
                name={'Current location'} />
 
        <InfoWindow
          marker={this.state.activeMarker}
          visible={this.state.showingInfoWindow}>
            <div>
              <h1>{this.state.selectedPlace.name}</h1>
            </div>
        </InfoWindow>
      </Map>
    )
  }
});

Events

The <InfoWindow /> throws events when it's showing/hiding. Every event is optional and can accept a handler to be called when the event is fired.

<InfoWindow
  onOpen={this.windowHasOpened}
  onClose={this.windowHasClosed}
  visible={this.state.showingInfoWindow}>
    <div>
      <h1>{this.state.selectedPlace.name}</h1>
    </div>
</InfoWindow>

onClose

The onClose event is fired when the <InfoWindow /> has been closed. It's useful for changing state in the parent component to keep track of the state of the <InfoWindow />.

onOpen

The onOpen event is fired when the window has been mounted in the Google map instance. It's useful for keeping track of the state of the <InfoWindow /> from within the parent component.

The GoogleApiWrapper automatically passes the google instance loaded when the component mounts (and will only load it once).

Manually loading the Google API

If you prefer not to use the automatic loading option, you can also pass the window.google instance as a prop to your <Map /> component.

<Map google={window.google} />

Contributing

git clone https://github.com/fullstackreact/google-maps-react.git
cd google-maps-react
npm install
make dev

The Google Map React component library uses React and the Google API to give easy access to the Google Maps library.

Fullstack React Book

This Google Map React component library was built alongside the blog post How to Write a Google Maps React Component.

This repo was written and is maintained by the Fullstack React team. In the book we cover many more projects like this. We walk through each line of code, explain why it's there and how it works.

This app is only one of several apps we have in the book. If you're looking to learn React, there's no faster way than by spending a few hours with the Fullstack React book.