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API Reference | GeoFire for JavaScript

Table of Contents

GeoFire

A GeoFire instance is used to read and write geolocation data to your Firebase database and to create queries.

new GeoFire(firebaseRef)

Creates and returns a new GeoFire instance to manage your location data. Data will be stored at the location pointed to by firebaseRef. Note that this firebaseRef can point to anywhere in your Firebase database.

// Initialize the Firebase SDK
firebase.initializeApp({
  // ...
});

// Create a Firebase reference where GeoFire will store its information
var firebaseRef = firebase.database().ref();

// Create a GeoFire index
var geoFire = new GeoFire(firebaseRef);

GeoFire.ref()

Returns the Firebase reference used to create this GeoFire instance.

var firebaseRef = firebase.database().ref();
var geoFire = new GeoFire(firebaseRef);

var ref = geoFire.ref();  // ref === firebaseRef

GeoFire.get(key)

Fetches the location stored for key.

Returns a promise fulfilled with the location corresponding to the provided key. If key does not exist, the returned promise is fulfilled with null.

geoFire.get("some_key").then(function(location) {
  if (location === null) {
    console.log("Provided key is not in GeoFire");
  }
  else {
    console.log("Provided key has a location of " + location);
  }
}, function(error) {
  console.log("Error: " + error);
});

GeoFire.set(keyOrLocations[, location])

Adds the specified key - location pair(s) to this GeoFire. If the provided keyOrLocations argument is a string, the single location will be added. The keyOrLocations argument can also be an object containing a mapping between keys and locations allowing you to add several locations to GeoFire in one write. It is much more efficient to add several locations at once than to write each one individually.

If any of the provided keys already exist in this GeoFire, they will be overwritten with the new location values. Locations must have the form [latitude, longitude].

Returns a promise which is fulfilled when the new location has been synchronized with the Firebase servers.

Keys must be strings and valid Firebase database key names.

geoFire.set("some_key", [37.79, -122.41]).then(function() {
  console.log("Provided key has been added to GeoFire");
}, function(error) {
  console.log("Error: " + error);
});
geoFire.set({
  "some_key": [37.79, -122.41],
  "another_key": [36.98, -122.56]
}).then(function() {
  console.log("Provided keys have been added to GeoFire");
}, function(error) {
  console.log("Error: " + error);
});

GeoFire.remove(key)

Removes the provided key from this GeoFire. Returns a promise fulfilled when the removal of key has been synchronized with the Firebase servers. If the provided key is not present in this GeoFire, the promise will still successfully resolve.

This is equivalent to calling set(key, null) or set({ <key>: null }).

geoFire.remove("some_key").then(function() {
  console.log("Provided key has been removed from GeoFire");
}, function(error) {
  console.log("Error: " + error);
});

GeoFire.query(queryCriteria)

Creates and returns a new GeoQuery instance with the provided queryCriteria.

The queryCriteria describe a circular query and must be an object with the following keys:

  • center - the center of this query, with the form [latitude, longitude]
  • radius - the radius, in kilometers, from the center of this query in which to include results
var geoQuery = geoFire.query({
  center: [10.38, 2.41],
  radius: 10.5
});

GeoQuery

A standing query that tracks a set of keys matching a criteria. A new GeoQuery is created every time you call GeoFire.query().

GeoQuery.center()

Returns the location signifying the center of this query.

The returned location will have the form [latitude, longitude].

var geoQuery = geoFire.query({
  center: [10.38, 2.41],
  radius: 10.5
});

var center = geoQuery.center();  // center === [10.38, 2.41]

GeoQuery.radius()

Returns the radius of this query, in kilometers.

var geoQuery = geoFire.query({
  center: [10.38, 2.41],
  radius: 10.5
});

var radius = geoQuery.radius();  // radius === 10.5

GeoQuery.updateCriteria(newQueryCriteria)

Updates the criteria for this query.

newQueryCriteria must be an object containing center, radius, or both.

var geoQuery = geoFire.query({
  center: [10.38, 2.41],
  radius: 10.5
});

var center = geoQuery.center();  // center === [10.38, 2.41]
var radius = geoQuery.radius();  // radius === 10.5

geoQuery.updateCriteria({
  center: [-50.83, 100.19],
  radius: 5
});

center = geoQuery.center();  // center === [-50.83, 100.19]
radius = geoQuery.radius();  // radius === 5

geoQuery.updateCriteria({
  radius: 7
});

center = geoQuery.center();  // center === [-50.83, 100.19]
radius = geoQuery.radius();  // radius === 7

GeoQuery.on(eventType, callback)

Attaches a callback to this query which will be run when the provided eventType fires. Valid eventType values are ready, key_entered, key_exited, and key_moved. The ready event callback is passed no parameters. All other callbacks will be passed three parameters:

  1. the location's key
  2. the location's [latitude, longitude] pair
  3. the distance, in kilometers, from the location to this query's center

ready fires once when this query's initial state has been loaded from the server. The ready event will fire after all other events associated with the loaded data have been triggered. ready will fire again once each time updateCriteria() is called, after all new data is loaded and all other new events have been fired.

key_entered fires when a key enters this query. This can happen when a key moves from a location outside of this query to one inside of it or when a key is written to GeoFire for the first time and it falls within this query.

key_exited fires when a key moves from a location inside of this query to one outside of it. If the key was entirely removed from GeoFire, both the location and distance passed to the callback will be null.

key_moved fires when a key which is already in this query moves to another location inside of it.

Returns a GeoCallbackRegistration which can be used to cancel the callback. You can add as many callbacks as you would like for the same eventType by repeatedly calling on(). Each one will get called when its corresponding eventType fires. Each callback must be cancelled individually.

var onReadyRegistration = geoQuery.on("ready", function() {
  console.log("GeoQuery has loaded and fired all other events for initial data");
});

var onKeyEnteredRegistration = geoQuery.on("key_entered", function(key, location, distance) {
  console.log(key + " entered query at " + location + " (" + distance + " km from center)");
});

var onKeyExitedRegistration = geoQuery.on("key_exited", function(key, location, distance) {
  console.log(key + " exited query to " + location + " (" + distance + " km from center)");
});

var onKeyMovedRegistration = geoQuery.on("key_moved", function(key, location, distance) {
  console.log(key + " moved within query to " + location + " (" + distance + " km from center)");
});

GeoQuery.cancel()

Terminates this query so that it no longer sends location updates. All callbacks attached to this query via on() will be cancelled. This query can no longer be used in the future.

// This example stops listening for all key events in the query once the
// first key leaves the query

var onKeyEnteredRegistration = geoQuery.on("key_entered", function(key, location, distance) {
  console.log(key + " entered query at " + location + " (" + distance + " km from center)");
});

var onKeyExitedRegistration = geoQuery.on("key_exited", function(key, location, distance) {
  console.log(key + " exited query to " + location + " (" + distance + " km from center)");

  // Cancel all of the query's callbacks
  geoQuery.cancel();
});

GeoCallbackRegistration

An event registration which is used to cancel a GeoQuery.on() callback when it is no longer needed. A new GeoCallbackRegistration is returned every time you call GeoQuery.on().

These are useful when you want to stop firing a callback for a certain eventType but do not want to cancel all of the query's event callbacks.

GeoCallbackRegistration.cancel()

Cancels this callback registration so that it no longer fires its callback. This has no effect on any other callback registrations you may have created.

// This example stops listening for new keys entering the query once the
// first key leaves the query

var onKeyEnteredRegistration = geoQuery.on("key_entered", function(key, location, distance) {
  console.log(key + " entered query at " + location + " (" + distance + " km from center)");
});

var onKeyExitedRegistration = geoQuery.on("key_exited", function(key, location, distance) {
  console.log(key + " exited query to " + location + " (" + distance + " km from center)");

  // Cancel the "key_entered" callback
  onKeyEnteredRegistration.cancel();
});

Helper Methods

GeoFire.distance(location1, location2)

Static helper method which returns the distance, in kilometers, between location1 and location2.

location1 and location1 must have the form [latitude, longitude].

var location1 = [10.3, -55.3];
var location2 = [-78.3, 105.6];

var distance = GeoFire.distance(location1, location2);  // distance === 12378.536597423461

Promises

GeoFire uses promises when writing and retrieving data. Promises represent the result of a potentially long-running operation and allow code to run asynchronously. Upon completion of the operation, the promise will be "resolved" / "fulfilled" with the operation's result. This result will be passed to the function defined in the promise's then() method.

If you are unfamiliar with promises, check out this blog post. Here is a quick example of how to consume a promise:

promise.then(function(result) {
  console.log("Promise was successfully resolved with the following value: " + result);
}, function(error) {
  console.log("Promise was rejected with the following error: " + error);
})