how to import JSON file for node and link data

[jsheltonwilson]

I am relatively new to javascript so I apologize but I am trying to figure out a way to import an external JSON file to be used to create the nodes and links. From looking at the demo, I thought graph.loadJSON would be where I can put my filename but in the example, my understanding is that graph.loadJSON(graphJSON) is just calling the variable that was made holding the data.