Interpretation of var inside JavaScript if statement

Question

I have been taught to define variables at the top, regardless of their position in your code, as this is how JavaScript will interpret things. So, my understanding is that:

var foo = "Bob";

if (2 + 2 === 4) {
    var car = "Blah";
}

Will be interpreted like:

var foo = "Bob",
    car;

if (2 + 2 === 4) {
    car = "Blah";
}

Is my understanding correct? I've always tried to position my variable definitions at the top of the current scope, but sometimes those variables are only needed inside an if statement, so defining them outside seems a bit odd - is this still best practice?

Answer 1

Yes. var statements are hoisted (which is why best practise is to use them at the top of the function — it avoids confusion from people assuming block scope instead of function scope)