XML : Accessing element height in NativeScript

I am trying to write a native script app which retrieves the rendered height of the bottle view/element in my xml. I have tried the following code, but unfortunately, I get an error (shown below). Any guidance would be much appreciated.

JS:

  var viewModule = require("ui/core/view");  var page;    exports.fabTap = function (args) {        page = args.object;        var bottle = page.getViewById("bottle");        console.log("Height: " + bottle.height);    }    

XML:

  <Page xmlns="http://schemas.nativescript.org/tns.xsd" xmlns:FAB="nativescript-floatingactionbutton" actionBarHidden="true" loaded="pageLoaded">    <GridLayout columns="*, *, *, *" rows="15*, 5*, 20*, 5*, 5*, 5*, 5*, 20*, 20*" width="100%" height="100%" style.backgroundColor="white" >      <Image src="res://logo" row="0" col="1" colSpan="2" stretch ="aspectFit" class="logo"/>      <Image id="bottle" src="res://bottle_outline" row="2" col="0" rowSpan="6" colSpan="2" stretch="aspectFit"/>    </GridLayout>  </Page>    

Cannot read property 'height' of undefined.