https://github.com/getify/You-Dont-Know-JS/tree/1st-ed
If it’s not a primitive, it’s an object.
Undefined → when a variable doesn’t have a value assigned to it or for a function that doesn’t return anything
Null → something you assign explicitly
Objects can be mutated.
Functions are 'first class citizens' in JavaScript and can be assigned to variables. Or passed as an argument to another function.
<aside> 💡 Use const unless you know it’s going to be changed for sure.
</aside>
Objects → key value pairs
Statements are a command for the computer to do something.
Expression are something that return a value.
console.log(/* Some chunk of JS here */);
// if it returns an error that chunk is a statement
// if it returns a value that means its an expression!
Expressions can't exist on their own. They're always part of a statement.