How to define default value of a variable containing null if it's null?

Question

Hello everyone, I want to display another value of a variable containing promt if the user clicks ok or clicks anywhere else in the body(if it's HTML page). Here's the code
var name = prompt("Enter your name");

var nameLength = name.value.length;
if (nameLength == 0) {
name = "Visitor";
}

alert("Thanks for Watching " + name);

But it's giving error that can't read property

Answer 1

The error is hinting that the property doesn't exist.
Have you already considered something like this?

let x = prompt()
if (x) {
console.log("x = ", x);
}
else {
x = "default";
console.log("No input, x = ", x);
}