Grate.I use to study this but being a pharmacist at certain point in my life I just had to let it go and give more attention to my area of studies.I know I really missed alot not studying it ...
Some common rules I was given as at then :

To Avoid Common JavaScript Mistakes
Using == and === Operators wrongly. Because they are both comparison operators and return boolean values. ...
No block-level scope. ...
Missing function Parameters. ...
Undefined !== ...
Addition and concatenation.