Avoid problems

Why did we go over these examples? Should we remember these peculiarities all the time? Well, not really. Actually, these tricky things will gradually become familiar over time, but there’s a solid way to avoid problems with them:

Treat any comparison with undefined/null except the strict equality

===

with exceptional care.
Don’t use comparisons

>= > < <=

with a variable which may be null/undefined, unless you’re really sure of what you’re doing. If a variable can have these values, check for them separately.