Data types – both JavaScript and Python are dynamically typed!

In Chapter 3, Nitty-Gritty Grammar, we discussed using typeof() to ascertain what a variable's data type is and using let and const to define them. There's an interesting fact about JavaScript that Python shares: both are dynamically typed. As opposed to statically typed languages such as Java, JavaScript's variable types can change over the course of a program. This is one reason why typeof() can come in handy.

Let's take a look at a quick example contrasting JavaScript with Java:

Java	JavaScript
int age; age = 38; age = "thirty-eight";	let age age = 38 age = "thirty-eight"

If we tried to run the Java code, we'd get an error stating that the types are incompatible. In Java, variables have a type. When we run the JavaScript code, however, everything's just fine. In JavaScript, values have a type.

It's also important to know that JavaScript is weakly typed...