Find Leaflet map object after initialisation

16
votes

I'm trying to change some things on a map that is already initialised by another script, using the Leaflet library. This other script did not store the map-object in a global variable, or in any other location I can access with my script. So currently there is a map on my page, but I don't have the map object.

What I'd like to do is to retrieve the object of an already-initialised map, to make changes to it. For example, if there'd exist a function L.getMap('myID') I'd like to use such a method to retrieve the map object linked to the container myID.

TL;DR: Is there a way to get a map object of an already-initialised leaflet map, using the id of the container?

2
javascriptleafletmediawiki
How do you init your map? - Fabiano Taioli
What is the other script? - Fabiano Taioli
@FabianoTaioli I'm working on a MediaWiki extension, which uses mediawiki.org/wiki/Extension:Maps to load the maps. I've tried looking through the code of that extension, but it doesn't seem to store the map variable anywhere accessible. - Joeytje50
I have no experience with the Mediawiki Maps extension, however I found this JS file in the source code which indicates that a window.maps variable is created with a list of maps. I don't know whether this contains map objects or simply a list of (to be initiated) maps... - Sidney Gijzen
Do you have the possibility to execute some JS before the map is initialized? - ghybs

2 Answers

3
votes

You can access the map from the global array created by the mediawiki extension.

Es: for accessing the first map of the page

window.maps.leafletList[0].map.getCenter()
32
votes

For the record, in case you have the possibility to inject / execute some JS code before the map is initialized (i.e. before the "other script" executes), you can very easily customize Leaflet to keep a reference to each created maps.

E.g. using the addInitHook constructor hook on L.Map class:

// Before map is being initialized.
var mapsPlaceholder = [];

L.Map.addInitHook(function () {
  mapsPlaceholder.push(this); // Use whatever global scope variable you like.
});

// "Other script", can be in its own separate <script> and JS file.
L.map('mapId'); // The map object is pushed into `mapsPlaceholder` array.

// Then retrieve the map object to further manipulate the map.
var map = mapsPlaceholder.pop();

Demo: https://plnkr.co/edit/mywpSbfRPFOnJ8c1RNsZ?p=preview