Javascript "falsey" values

false.js

var falseyValues = [
  false,
  0,
  undefined,
  NaN,
  "",
  null
  ];

falseyValues.map(function (x) {return x ? true : false;}); // [false, false, false, false, false, false]

/*
 * in &&-assignment JS will take the right-most truthy value, if the circuit isn't broken,
 * or the left-most (first) falsey value if it is:
 */

true && 1 // yields 1
true && 0 == true && 0 && 1 // yields 0
// ^ broken at value 0 -- everything else is ignored ^