Not quite. With square brackets, the expression is evaluated, so if it's a variable, its value is looked up. Consider:

    const name1 = person.name;
    const name2 = person['name'];
    const prop = 'name';
    const name3 = person[prop];
    const name4 = person['na'+'me'];

All of the above work and do the same thing. But not this:

const name5 = person[name]; 

(Under what circumstances would name5 mean the same things as the others?)

Good question. map collects all the return values into a new array, while forEach ignores the return values (if any).

So, you use map when you want a new array (as with the Plotting assignment or a Python list comprehension), and forEach when you just want to iterate (like a Python for loop).

JSON is a standard way to transmit and store data. It's easily machine readable, so machine-to-machine communication is ideal. But it's also human-friendly, so it makes a good way for coders to look at data.

So, that covers a lot of ground.

There are whole databases designed to store data represented as JSON (so-called NoSQL databases).

Great!