Is there a way to know which deep link required authentication?

[erlend_thune]

When a user tries to access a Canvas a course that requires authentication, she is forwarded to the login page. We would like to know which course the user tries to access and perform some actions in a custom javascript, depending on the course id.

F.ex. 

1. Try to access https://bibsys.instructure.com/courses/499/pages/statistikk-v-dot-1-1

2. When clicking the link in 1. you are forwarded to https://bibsys.instructure.com/login and then on to https://bibsys.instructure.com/login/canvas

3. At this point, my custom javascript is loaded. How can I find out that the user tries to access course 499?

In step 1, this header seems to contain the information (i=499): 

x-canvas-meta:

q=923;a=1;g=LS7iTMBta74uL8qlc1UeDi4luVWdtrKg71qjY1Ib;s=3727;c=cluster15;z=eu-west-1c;o=wiki_pages;n=show;t=Course;i=499;b=2445556;m=2445556;u=0.08;y=0.00;d=0.01;

But that information does not seem to be available in step 3.