1.1 KiB
1.1 KiB
The result is: error.
Try running it:
let x = 1;
function func() {
*!*
console.log(x); // ReferenceError: Cannot access 'x' before initialization
*/!*
let x = 2;
}
func();
In this example we can observe the peculiar difference between a "non-existing" and "unitialized" variable.
As you may have read in the article , a variable starts in the "uninitialized" state from the moment when the execution enters a code block (or a function). And it stays uninitalized until the corresponding let statement.
In other words, a variable technically exists, but can't be used before let.
The code above demonstrates it.
function func() {
*!*
// the local variable x is known to the engine from the beginning of the function,
// but "unitialized" (unusable) until let ("dead zone")
// hence the error
*/!*
console.log(x); // ReferenceError: Cannot access 'vx before initialization
let x = 2;
}
This zone of temporary unusability of a variable (from the beginning of the code block till let) is sometimes called the "dead zone".