Nested Blocks
You can introduce nested code blocks, for example, if you want to limit the scope of a variable.
let x = 10;
{
let y = 30;
x = y;
}
x == 30;
// The variable `y` is inaccessible here.
In contrast to JavaScript, variables introduced within the nearest local namespace context (e.g., a code block) exist only until the end of that context.