I now know what the prototypes

I finally know why you have to use === instead of ==,
I finally understood how the scope:
var b = 4;
if (b === 4) {
var c = 5;
}

console.log (c); // Display 5 !!!!!

and also this!

Did you know that the functions are stored in variables?

I did not understand 100% of the book, but I really improved a lot.

To read urgently.