gistfile1.js

function t(a, b) {
  return a & b
    ? "first" : a
      ? "second" : b
        ? "third" : "default"
}

console.log(t(true, true))
console.log(t(true, false))
console.log(t(false, true))
console.log(t(false, false))

/* output
first
second
third
default
*/

function tt(a, b) {
  return (a && b) ? "first"
    : a ? "second"
    : b ? "third"
    : "default"
}