javascript .filter() true booleans

Question

function bouncer(arr) {
  // Don't show a false ID to this bouncer.
    function a(b) {
      if(b !== false) {
        return b;
      }
    }

    arr = arr.filter(a);
    return arr;
}

bouncer([7, 'ate', '', false, 9]);

I have to return true boolean statements only, and when I run this code, it works. However, I am quite confused because my "if statement" will work whether it's b !== true or b !== false. Could someone please explain the reason why this works both ways?

Answer 1

I was solving a similar problem and came up with this:

function bouncer(arr) {
  return arr.filter(Boolean);
}
bouncer([7, 'ate', '', false, 9]);
// returns ['7','ate','9']