It looks like this is a handlebars helper.

Handlebars is a temptating language.

I've never used handlebars but I'm guessing this is syntactic sugar for non-programmers. Like:

<div>{{if is-even myVariable}} it's even {{else}} it's odd {{endif}}</div>

This is awesome but I don't really understand.

The purported issue is that they don't have explicit consent for some data points. They apparently responded by saying they were going to charge a subscription.

Why wouldn't they just get consent? I'm sure most fb users will just agree to anything put in front of them.

Oh man, in js we have a package for this magic.