Challenge at the end of the hoisting tutorial

Hi Mark,

You start off with this code:

function elevatorCloseButton(pushed) {
    if (pushed) {
        var status = "I'll close when I'm ready.";
    }
}

So it looks like the status variable is declared inside the if block and then assigned a string. Some languages have block level scope. This means that the status variable would only be available inside that if block because that's where it was declared. If you had some additional code inside that function after the if block it would not be able to use that status variable. It would be undefined after the if block.

Javascript does not have block level scope but it has function level scope. So what javascript does for you is it "hoists" the variable declaration to the top of the function.

So javascript sees the above code as if you had written:

function elevatorCloseButton(pushed) {
    var status;

    if (pushed) {
        status = "I'll close when I'm ready.";
    }
}

Even though you've written your code like the first block, it is going to be run like the second block.

All the challenge is asking you to do is make that explicit rather than have javascript do it implicitly behind the scenes for you. Write it the second way because that's what's really happening.

Does that make sense?

That's awesome! Thank you very much Jason. I really appreciate the great explanation.