I am working on a GIS API, that uses OpenLayers. I initialize the map lke this:

xgis.map = OpenLayers.Class(OpenLayers.Map, {
    var mapOptions = {};
    mapOptions.allOverlays = false;
        more mapOptions here
    OpenLayers.Map.prototype.initialize.apply(this, ['map', mapOptions]);

Of course, I do this because I want to create my own methods, like this one, for example.

xgis.map.prototype.zoom(action) {
    switch(action) {
        case 'in:
            this.zoomIn();    // Uses the OpenLayers zoomIn method
        case 'out:
            this.zoomOut();    // Uses the OpenLayers zoomOut method

The problem is this 'zoom' method I created is not recognized as a function (I get: number is not a function), because OpenLayers has a 'zoom' numeric value where it stores the zoom.

Is there a way to use inheritance and access the parent's methods like this?


This would definitely fix the 'zoom' name problem.

1 Answer 1


You are writing bad, it must be:

xgis.map.prototype.zoom = function(action) { ... }

Anyway, it is better you follow the Ol code conventions. To create subclasses you must create methods inside class definition, something like:

xgis.map = OpenLayers.Class(OpenLayers.Map, {
    someAttribute: 'someValue'.
    someMethod: function() {

    CLASS_NAME: 'your_class_name'

You can find a custom control code at: http://acanimal.github.io/Openlayers-Cookbook/recipes/ch08/crossControl.js Which is part of the samples of the OpenLayers Cookbook. See more samples at http://acanimal.github.io/Openlayers-Cookbook/ the sample "chapter8-custom control".

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