Conditionally setting configs in ExtJS 6?

I have an Ext.Img that I would like to set the src config of based upon a condition. Is there a simple way to accomplish this? I am thinking something like

if(condition){ src: 'image1.png'} else { src: 'image2.png'}

but this obviously won't work. I've using some of the techniques mentioned in this thread, by adding a different image item based on the condition but all I get are errors or no items will be added to the parent panel.