Doing this is a bad idea as draw() is executed at least 30 times per second. You could attach it to an event associated to an element in your DOM. For example, when a mouse is clicked or a key is typed in a field. Is that what you mean?
In your first code, I vbelieve those fields in the header need to be placed within quotation marks. If you check your console output, you should get some errors indicating you need to fix those fields. Did you see those messages?
Regarding your url, as Kevin mentioned, it is important that you get a response when you load that request directly. I wasn’t able to get it to work. I didn’t know if it was because the request wa ill-formulated or there was an error in the service. But it seems you got it to work, so that is good for the time being. It is important to have a runnable example here in the forum to be able to reproduce the problems and solve questions efficiently.
Kf