Learn ECMAScript - Second Edition

Classes are not hoisted!

You can call a function before it's defined; that is, function calls can be made before the function definition. But, you cannot use a class before it's defined. Trying to do so in classes will throw the ReferenceError exception.

Here is an example to demonstrate this:

myFunc(); // finefunction myFunc(){} var obj = new myClass(); // throws errorclass myClass {}