Its an easy to use password strenght meter, made from many examples found on the web.
You should have imported jQuery and Bootstrap. Then copy the "checkpassword(pwd)" method in a suitable place, and call it in the keyup event of your input password, and that's it!
Non complex strenght meter with a nice design, it only has 3 options of meter: weak - letters medium - letters + numbers stron - letters + numbers + special chars.