Hoisting

console.log(greet('Ana'));

function greet(name) {
    return 'Hello, ' + name;
}

Hello, Ana

The call on the first line works, although greet is declared below it. The reason is that JavaScript does not run a file or a function body strictly from top to bottom. It first prepares the scope, and only then runs the statements.

Two Phases: Setup, Then Execution

Before any line of a scope runs, JavaScript scans the scope for declarations and creates a binding for each name it finds