How to know the duration of a YouTube video before it starts playing?

Question

YouTube

I can't figure out why I have all the videos 1 second longer before they start playing.
Codepen.io example
Line 85: console.log(Math.floor(player.getDuration()));
By F12 we open the Console and see 17 sec, this is already rounded up from 16.7 sec.
Next, run the video, and get 16 seconds!
How so?
And this is with almost any video. 1 sec is certainly not critical, but somehow it hurts the eye.

Answer 1

read about Math.floor)))
Replace withplayer.getDuration().toFixed(1)