We need to create a new /api/get-campaign-categories route.

This will allow the client side code to access the category list by using the campaign ID as a URL parameter.

e.g. /api/get-campaign-categories?campaign=4

This return the JSON with this format from the server:

{ 
    "name": "Wiki Loves Love In Cameroon", 
    "categories": [
        {"name": "Category:Wiki Loves Women - Events in Nigeria", "depth": 0}, 
        {"name": "Category:Wiki Loves Monuments 2018 in R\u00e9union", "depth": 0}
    ]
}

Change 511787 had a related patch set uploaded (by Eugene233; owner: Eugene233):
[labs/tools/Isa@master] Add API route to get campaign categories from the client side

https://gerrit.wikimedia.org/r/511787

Change 511787 merged by jenkins-bot:
[labs/tools/Isa@master] Add API route to get campaign categories from the client side

https://gerrit.wikimedia.org/r/511787