What's the output?

Each function has its own execution context (or scope). The getName function first looks within its own context (scope) to see if it contains the variable name we're trying to access. In this case, the getName function contains its own name variable: we declare the variable name with the let keyword, and with the value of 'Sarah'.

Variables with the let keyword (and const) are hoisted, but unlike var, don't get initialized. They are not accessible before the line we declare (initialize) them. This is called the "temporal dead zone". When we try to access the variables before they are declared, JavaScript throws a ReferenceError.

If we wouldn't have declared the name variable within the getName function, the javascript engine would've looked down the scope chain. The outer scope has a variable called name with the value of Lydia. In that case, it would've logged Lydia.

let name = 'Lydia';

function getName() {
  console.log(name);
}

getName(); // Lydia