Hoisting of functions inside conditionals

I understanding how hoisting in javascript occurs, functions are hoisted before variables, and only the declarations are hoisted. But When I came across hoisting inside if/else conditionals, like this one:

foo(); // "b is the output"
var a = true;

if (a) {
  function foo() { console.log("a"); }
}
else {
  function foo() { console.log("b"); }
}

Now the conditional is true, so according to the if block, a should have been the output, but due to some kind of hoisting I assume b is the output.

So how is b the output?