ENV server->js data pattern

gistfile1.txt

Why this is useful:

1. All data in ENV is coming from the server, so it's easy to differentiate data coming from the server and static data when reading through JS.
2. If you put the {{ env_js }} in the root template, it'll be usable by in all templates that inherit from it. That means you don't need to adjust the template to share data to the client-side.
3. Only one new global variable instead of one per thing coming from the server.

handler.py

class SomeHandler(request_handler.RequestHandler):
    def get(self):
        user_data = user_models.UserData.current()

        # If I want to propagate more data to the clientside, all I have to do is add to this dict
        env_js = {
            "user_data" : user_data.user_id if user_data else None
        }

        self.render_jinja2_template('template.html', {
            "env_js" : jsonify.jsonify(env_js, camel_cased=True)
        })

template.html

{% if env_js %}
<script>var ENV = {{ env_js }};</script>
{%- endif %}

usage.js

console.log(ENV.userId);