Web Design: Line effect with block reveal style animation on link click

I'm currently trying to figure out how a current trend can be coded, I've seen this effect used quite often as seen here when using the navigation www.bearideas.fr,

I've searched the web for some kind of explanation/tutorial as to how the lines and then ultimately the block reveal in each individual section but I can only find a plugin on typmanus which was a bit complicated for me to try and learn from and ultimately I couldn't get it working or understand.

I was wondering if anyone could point me in the direction of any tutorials they have come across involving this effect or possibly explain a little how it works.

Sorry if this is the incorrect place to ask as I understand my question is a little bit vague but any type of help would be appreciated.

Thanks in advance, Mike.