javascript - The context of this in a callback function

Question

I am dealing with an API where It was a method on the Instance which returns a callback function

   myPlayer.onPlay(function() {
            console.log(this)
        })

Now I would expect the context of this to be the player but it is not it is the callback function. I have tried binding the context of this like this but it doesn't work either.

I expected this to be myPlayer as that is the context in which the onPlay function was executed?

myPlayer.onPlay(function() {
        console.log(this)
    }).bind(this)

How would I get the context to be the instance of the player? Am i missing something?

question from:https://stackoverflow.com/questions/65599727/the-context-of-this-in-a-callback-function

Answer 1

You would have to do

myPlayer.onPlay(
  function() {
    console.log(this);
  }.bind(myPlayer)
);

Since you haven't provided what .onPlay will return, I don't think it would return an object with a bind method. So you have to use bind on the function itself. You can't use this in the bind if you want it to be the myPlayer, because in your current call scope this doesn't mean something. It can mean something, but it most likely won't be the player, or else you would have done this.onPlay. You have to bind myPlayer with bind, not this.