Technically a "callback function" is one that's called at a later point in time, like asynchronously, as in "we'll call you back later".
In this case it's just a "function", nothing so exotic. This function is called immediately if/when a substitution is to be performed.
It's easy to understate how powerful a tool this can be though, so good article about using it!
Are you sure you want to hide this comment? It will become hidden in your post, but will still be visible via the comment's permalink.
Hide child comments as well
Confirm
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
Technically a "callback function" is one that's called at a later point in time, like asynchronously, as in "we'll call you back later".
In this case it's just a "function", nothing so exotic. This function is called immediately if/when a substitution is to be performed.
It's easy to understate how powerful a tool this can be though, so good article about using it!