falsy.js

// JavaScript has 6 falsy values (that evaluate to false when coerced to a boolean)
// false
// 0
// ""
// null
// undefined
// NaN

// Using != null, we can safely check against null and undefined rather than multiple underscore functions, typeofs, etc

var obj = {
  zero: 0,
  falsed: false,
  empty: "",
  nan: NaN,
  nulled: null,
  undef: undefined,
};

// the ones we don't want to evalute as false
// 1 :- [object Object]
// 2 :- 0
// 3 :- false
// 4 :- ""
// 5 :- NaN

console.info("1 :- " + (obj != null ? obj : null));
console.info("2 :- " + (obj.zero != null ? obj.zero : null));
console.info("3 :- " + (obj.falsed != null ? obj.falsed : null));
console.info("4 :- " + (obj.empty != null ? '""' : null));
console.info("5 :- " + (obj.nan != null ? obj.nan : null));

// The ones we care about
// 6 :- null
// 7 :- null
console.info("6 :- " + (obj.undef != null ? obj.undef : null));
console.info("7 :- " + (obj.nulled != null ? obj.undef : null));