So, this is above my head, but I figured out that the Epicor Edge Agent is actually QZ ( qz | Home). For more technically inclined users, there is some good documentation on their site. As an example, they give code to get a list of printers.
function findPrinters() {
qz.printers.find().then(function(data) {
var list = '';
for(var i = 0; i < data.length; i++) {
list += " " + data[i] + "<br/>";
}
displayMessage("<strong>Available printers:</strong><br/>" + list);
}).catch(function(e) { console.error(e); });
}