adding examples for promises that support try/catch for exceptions

Author: krpatter-intc

examples/02 - callbacks/callbacks.py

@@ -8,6 +8,13 @@
 def py_random():
     return random.random()
 
+@eel.expose
+def py_exception(error):
+    if error:
+        raise ValueError("Test")
+    else:
+        return "No Error"
+
 def print_num(n):
     print('Got this from Javascript:', n)
 

examples/02 - callbacks/web/callbacks.html

@@ -20,7 +20,25 @@
 
         // Do the same with an inline callback
         eel.py_random()(n => console.log('Got this from Python: ' + n));
-        
+
+        // show usage with promises
+        // show no error
+        eel.py_exception(false)().then((result) => {
+                // this will execute since we said no error
+                console.log("No Error")
+            }).catch((result) => {
+                console.log("This won't be seen if no error")
+            }
+        );
+        // show if an error occurrs
+        eel.py_exception(true)().then((result) => {
+                // this will not execute
+                console.log("No Error")
+            }).catch((result) => {
+                console.log("This is the repr(e) for an exception " + result.errorText);
+                console.log("This is the full traceback:\n" + result.errorTraceback);
+            }
+        )
         </script>
     </head>