Use semicolons to end statements;
Use let and const to avoid globals;
Always assign to let and const;
Hoisting is just bizarre: just avoid it;
Do not reassign const objects or const arrays: const shouldn't change;
Number can be integer or floating point =s
Don't reassign to different data types: it introduces bugs;
Plus (+) operator converts number to strings ('37'+7='377'); other operators don't ('37'-7=30) =s
Specify all elements in your array, please.
Numeric literal as the name of a property is weird. Just go with something valid to be accessed by a dot (".");
Interpolation? Yes. Except backtick is weird...