JavaScript Error: Uncaught TypeError: foo is not a function

Question

For some reason JavaScript doesn\'t seem to recognise my function.

I have a button in some HTML:

Answer 1

Instead of using the onclick attribute, it is much cleaner to add the event listener in JavaScript, like so:

$('#lightOn').on('click', function() {
  $("#lightOn").addClass("active");
  $("#lightOff").removeClass("active");
  socket.emit("setting", {"light":"on"});
});

On