What does ‘::’ (double colon) do in javascript for events?

Question

I saw this code and I\'m scratching my head trying to decide how it works.

Answer 1

As mentioned in this answer of What does ‘::’ (double colon) do in javascript?

:: is a ES2016 operator that is shorthand for bind. This answer intends to assist those that have encountered :: since the ES2016 spec, however, does not apply to the context in which this question was asked.