Why doesn't my app work?

In your conditional statement, you have a triple equal sign. In other words, you're checking whether or not the guess is identical (strict equal) to the random number generated. What you want is two equal signs, or checking whether the random number is equal (loose equal) to the guess.

You can read the documentation on that here.

But essentially, loose equal (equal, ==) will:

perform a type conversion when comparing two things, and will handle NaN, -0, and +0 specially to conform to IEEE 754 (so NaN != NaN, and -0 == +0);

Whereas strict equal (identical, ===):

will do the same comparison as double equals (including the special handling for NaN, -0, and +0) but without type conversion; if the types differ, false is returned.