Cordova provides you with a javascript API. They try to follow standards when possible. Firefox OS is built on web standards too. Sometimes they use the same API. How can a plugin developer access Firefox OS API when they clash?

Cordova provides us with a modulemapper library to access the original values of overwritten properties. Let’s take a look at how the battery-status plugin uses modulemapper:

var mozBattery = cordova.require('cordova/modulemapper').getOriginalSymbol(window, 'navigator.battery');

The variable mozBattery now points to the original navigator.battery. The first parameter to getOriginalSymbol is the context, pretty much always window. The second is the value you want to get. To find out what value to use on the second parameter, check the <js-module> element in the plugin’s plugin.xml configuration file. For the battery-status plugin it is:

<js-module src="www/battery.js" name="battery">
    <clobbers target="navigator.battery" />
</js-module>

The <clobbers> element’s target attribute has the value that was overwritten.