PHP Websocket undefined in Edge Browser
Are you sure you are actually writing WebSocket in your code? The error says that Websocket is not defined (with non-capitalized s).
The actual classname is WebSocket with a capital S.
Please confirm that the code you pasted as an example is really the same as the one you have in your application.
EDIT
After some further discussion in the comments I believe that WebSocket support might be disabled in your browser. WebSocket should be supported in your browser version (11.0.0600.18537) according to my own experiment and Can I Use.