How to detect page navigation on YouTube and modify its appearance seamlessly?

Question

I\'m making a simple Chrome extension to add up the length of each video in a YouTube playlist and insert the total length in the page. I\'ve succeeded at that, but my scrip

Answer 1

2017 answer:

I use this for new Material Design version Youtube

body.addEventListener("yt-navigate-finish", function(event) {
    // code here
});

and this for old Youtube

window.addEventListener("spfdone", function(e) {
    // code here
});

code come from 2 script I wrote call
"Youtube subtitle downloader" and "Youtube auto subtitle downloader".

both of them work, I tested.

if you are interested in my script and want know more detail:
https://github.com/1c7/Youtube-Auto-Subtitle-Download