Part one's claim that using the 'new' keyword is somehow implicitly bad needs more to back it up than Douglas Crockford saying so. Douglas Crockford's opinions are just opinions. Is it slower in certain JS runtimes? Harder to read? Less maintainable?
Anyway, re: part 2
You shouldn't encourage the use of 'value || defaultValue' without clearly, explicitly pointing out that this will prevent the use of falsy values as argument values - including 0, false, and an empty string... all values people actually want to use in some cases. It seems inexcusable to me that you would write:
"Based on the false-y rules we learned earlier, if we want to check if a variable is undefined, not null, and has a value then all we need to do is check the object itself."
Immediately after explaining how null and undefined are not the only falsy values in JS.
Anyway, otherwise it looks like you're sharing some good advice for newbies.
Anyway, re: part 2
You shouldn't encourage the use of 'value || defaultValue' without clearly, explicitly pointing out that this will prevent the use of falsy values as argument values - including 0, false, and an empty string... all values people actually want to use in some cases. It seems inexcusable to me that you would write:
"Based on the false-y rules we learned earlier, if we want to check if a variable is undefined, not null, and has a value then all we need to do is check the object itself."
Immediately after explaining how null and undefined are not the only falsy values in JS.
Anyway, otherwise it looks like you're sharing some good advice for newbies.